bluuebunny/crossref_metadata_2025 huggingface dataset:
Titania aerogels: Preparation and photocatalytic tests
Authors: Malinowska B. , Walendziewski J. , Robert D. , Weber J. V. , Stolarski M.
Published: March 2007

Titania aerogels are suggested as promising photocatalysts [1]. In the present study aerogels were
synthesised by sol‐gel method combined with supercritical drying. Tetraisopropyl orthotitanate was used as
a precursor, anhydrous methanol and isopropanol as solvents. Three aerogels were prepared using different
ways of synthesis. Volumes and surface areas of micro‐ and mesopores of each aerogel were determined.
XRD and SEM analyses were carried out. For comparison analyses were also performed for TiO2 P25 Degussa.
Aerogels′ BET surface areas ranged from 73 to 96 m2g-1. They indicate the crystalline structure of anatase. Finally photocatalytic tests were performed using water solution of p‐chlorophenol and 4‐hydroxybenzoic acid. Experiments were carried out in the Solar box simulating sun irradiation and on location. Aerogel Z513
prepared using 30% of precursor (tetraisopropyl orthotitanate) in isopropanol as a solvent indicates the best
photocatalytic activity towards p‐chlorophenol while Z516 prepared using 60% of precursor in methanol
towards 4‐hydroxybenzoic acid.
Preparation of TiO2 nanoparticles by Sol-Gel route
Authors: Bessekhouad Y. , Robert D. , Weber J. V.
Published: March 2007

Nanosized titanium oxide (TiO2) powders were prepared by emulsification‐gelation technology,
hydrolysis and reflux process. Starting precursor (Tetraisopropylorthotitanate ) was modified
by 1,4 cyclohexane diol (C6H14O2), hydrogen peroxide (H2O2) and Triethanol amine (C6H15NO3). Titanium tetrachloride was also used as precursor. The effect of methanol on ethanol solvent was also investigated.
The powders were analyzed by X‐ray diffraction (XRD) and BET technique. Scanning electron microscopy
observation was used for agglomerate observations. The photoactivity of the products obtained was taken
as efficiency of Benzamide photodegradations.
Heterogeneous photocatalytic reduction of ferrate(VI) in UV‐irradiated titania suspensions: Role in enhancing destruction of nitrogen‐containing pollutants
Authors: Sharma Virender K. , Winkelmann Kurt , Krasnova Yekaterina , Lee Changyoul , Sohn Mary
Published: March 2007

The results of the heterogeneous photocatalytic reduction of Fe(VI) in UV‐irradiated TiO2 suspensions
are presented and suggest indirect observation of the formation of Fe(V) by the photoreduction
of Fe(VI) with ecb− at TiO2 surfaces. Because Fe(V) selectively and rapidly oxidizes low reactivity pollutants
with the production of the non‐toxic by‐product, Fe(III), the photocatalytic reduction of Fe(VI) has a role in
pollution remediation processes. The experiments were conducted as a function of TiO2 suspension concentrations,
Fe(VI) concentrations, and pH in basic media. The initial rate of Fe(VI) reduction gave a fractional
order with respect to initial Fe(VI) concentrations and adheres to simple Langmuir‐Hinshelwood kinetics.
Results suggest that the surface reaction (Fe(VI) + ecb − →Fe(V)) is the rate‐controlling step. The photocatalytic
reduction of Fe(VI) in the presence of less reactive nitrogen‐containing species (ammonia, cyanate,
and fulvic acid) were also investigated. Enhancement in the rate of Fe(VI) reduction was observed. A reaction
scheme involving Fe(V) as an intermediate is presented which explains the faster photocatalytic oxidation
of pollutants in the presence of Fe(VI).
Photocatalytic reactors
Authors: Bouchy M. , Zahraa O.
Published: March 2007

Fundamental concepts for the design of photocatalytic reactors are recalled: specific rate, modeling
of the distribution of the irradiation, description and modeling of transport phenomena on the macroscopic
and macroscopic scales. These are required for establishing the reactor mass balance. A brief survey
of various reactors is given for solar or artificial light, gas‐ or liquid‐phase, slurry or fixed‐bed.
Highly selective deethylation of rhodamine B: Adsorption and photooxidation pathways of the dye on the TiO2/SiO2 composite photocatalyst
Authors: Chen Feng , Zhao Jincai , Hidaka Hisao
Published: March 2007

The photocatalytic degradation of Rhodamine B (RhB) with TiO2 and TiO2/SiO2 in the aqueous
dispersion was investigated under both the visible light (λ> 480 nm) and UV irradiation. The detailed photocatalytic
oxidative process of RhB under these different conditions was revealed by measurement of the
isoelectric points of the catalysts, UV‐VIS spectra, HPLC and LC‐MS. RhB adsorbs on the surface of TiO2/SiO2
particles by the positively‐charged diethylamino group while, in the case of net TiO2, it adsorbs through
the negatively‐charged carboxyl group under the experimental conditions (pH ∼ 4.3). In the RhB‐TiO2/SiO2
system, RhB firstly underwent a highly selective stepwise deethylation process before the destruction of the
chromophore structure under visible light irradiation. The average yield of the every deethylation step was
higher than 86%. It is confirmed that visible light‐induced photocatalytic degradation of dye proceeds on
the surface of catalysts rather than in the bulk solution and active oxygen species preferentially attack the
molecular portion that connects directly to the surface of catalysts. This work provides a possibility for the
modification of the surface characteristics of TiO2 to adsorb effectively the special colored organic molecules
in selective mode for selective modification or deeply extent photooxidation.
Methodologies and formalisms of resonance energy transfer in biophysics. Application to membrane model systems
Authors: Loura Luís M. S. , de Almeida Rodrigo F. M. , Prieto Manuel
Published: March 2007

The formalisms of resonance energy transfer (RET) to a distribution of acceptors are reviewed for several geometries relevant to membranes (planar, bilayer, multilayer) and random probe distribution.
Models for nonrandom probe distribution (mean concentration model, phase separation model) are presented. Selected examples of quantitative applications of RET to these systems are described. It is illustrated
how information about domain size, partition coefficients, phase composition, phase separation kinetics and bilayer aggregation can be obtained from time‐resolved RET data.
A comparative study on chemiluminescence propperties of some inorganic systems
Authors: Elbanowski Marian , Staninski Krzysztof , Kaczmarek Małgorzata , Lis Stefan
Published: March 2007

Chemiluminescence (CL) of selected inorganic reaction systems, generating ultraweak photon
emission, has been studied. The kinetics of the systems and their emission spectra have been characterised
by measurements with the use of the stationary and the flow methods of CL recording. The systems studied
contained cations at different oxidation degree such as Fe2+\3+, Cu+\2+, Co2+\3+, Eu2+\3+, CLO− anions and hydrogen peroxide without organic sensitisers. On the basis of the analysis of the spectra, in particular
systems emitters have been identified and mechanisms of the reactions have been proposed. The effect
of carbonate and azide ions and propylene carbonate on the yield of CL and spectral characterisation
of the systems studied has been evidenced and discussed. A possibility of the application of the systems Eu3+\ \H2O2 and Co2+\propylene carbonate\H2O2 for analytical purposes has been considered.
Fluorescence studies of photoactivated acidity of 2 ,2′‐Dihydroxy‐1 ,1′‐Binaphthalene
Authors: Ismail L. F. M. , Abdel-Mottaleb M. S. A.
Published: March 2007

Linear and multilinear relationships between some solvent polarity parameters and solvatochromic
shifts of absorption and fluorescence of 2 ,2′‐dihydroxy‐1 ,1′‐binaphthalene (DHBN) revealed strong
charge transfer excitations (formation of S1,CT with higher dipole moment) in this dipolar system. This dihydroxy
molecule with pKa(S0) of 10.9 becomes a weak acid with pKa(S1) of 6.8 in its first excited singlet state.
We studied the excited state proton‐transfer process from DHBN to the base water in acetonitrile solution
by means of fluorescence spectroscopy. We found that the process occurs via a 1: 1 very weak (with equilibrium
constant K = 9 × 10−3M−1) hydrogen‐bonded adduct between the photoacid DHBN and the base.
Moreover, the rate constant of fluorescence quenching of DHBN by some Lewis acids; Ag+1, Cu+2, Fe+2 or Fe+3 metal ions in methanol solution as well as the binding constant of the formed complexes are correlated
with the size and charge of the metal ion. Furthermore, photostability studies of DHBN in aqueous solutions
at different pHs point to photolability of DHBN with formation of different photo‐oxidation products similar
to simple naphthols.
Production of clusters and thin films of nitrides, oxides and carbides by pulsed laser ablation and deposition
Authors: Orlando S. , Paladini A. , Santagata A. , Marotta V. , Parisi G. P. , Satta M. , Scuderi D. , Catone D. , Giardini A. , Mele A.
Published: March 2007

A short introduction on the principles of laser‐matter interaction, material evaporation, plume
formation, its reactivity with suitable gases and finally deposition are here illustrated. Experiments by mass
spectrometry of formation of clusters, precursors of thin films and nanoparticles of oxides, nitrides and
carbides by pulsed laser ablation (PLA) are reported. Pulsed laser ablation of targets combined with an intense
atomic source produced by radiofrequency (RF), are discussed in terms of generating chemical reactions or
supplying the loss of volatile components.
Adsorption and reactions of CH2Br2 on TiO2: Effects of H2O and O2
Authors: Chen Meng-Tso , Lin Yu-Feng , Liao Li-Fen , Lien Chen-Fu , Lin Jong-Liang
Published: March 2007

The adsorption, thermo‐ and photo‐reactions of CH2Br2 on powdered TiO2 as well as the effects
of H2O and/or O2 have been studied by Fourier‐transform infrared spectroscopy. CH2Br2 is adsorbed
molecularly on the surface at 35∘C, interacting with the surface OH groups. It is completely desorbed or
decomposes to form CH3O(a) and HCOO(a) in a vacuum by 250∘C, probably via dioxymethylene (‐OCH2O‐). The presence of adsorbed H2O accelerates the formation of CH3O(a) and HCOO(a) from CH2Br2 dissociation. Adsorbed CH2Br2 decomposes to form CO(a), HCOO(a), CO3(a), and/or CO2(a) under 400 nm irradiation, depending
on whether the presence of H2O and/or O2. The presence of O2 increases the photoreaction rate of CH2Br2(a) and the photodecomposition is further accelerated with addition of H2O.
Towards a full understanding of water splitting in photosynthesis
Authors: Barber James
Published: March 2007

The capture and conversion of solar radiation by photosynthetic organisms directly or indirectly
provides energy for almost all life on our planet. About 2.5 billion years ago a remarkable biological “machine”
evolved known as photosystem two (PSII). This machine can use the energy of visible light (actually
red quanta of ∼ 1.8 eV) to split water into dioxygen and “hydrogen”. The latter is made available as reducing
equivalents, ultimately destined to convert carbon dioxide to organic molecules. In PSII, the “hydrogen”
reduces plastoquinone (PQ) to plastoquinol (PQH2). The water splitting process takes place at a catalytic
centre composed of 4 Mn atoms and the reactions involved are chemically and thermodynamically challenging.
The process is driven by a photooxidised chlorophyll molecule (P680•+) and involves electron/proton
transfer reactions aided by a redox active tyrosine residue situated between the 4 Mn cluster and P680. The
P680•+ species is generated by light induced rapid electron transfer (a few picoseconds) to a primary acceptor,
pheophytin a, before being transferred to PQ acceptors. Electron and x‐ray crystallographic studies are
now starting to reveal the structural basis for these reactions including the light harvesting processes. The
4 Mn atom‐cluster has been visualised as have the chlorophylls that constitute P680. The scene is now set
to fully elucidate the reactions of PSII and possibly mimic them in an artificial photochemical system that
could split water and produce hydrogen.
Photodynamics of clusters of the major components of the atmosphere
Authors: Aquilanti V. , Bartolomei M. , Cappelletti D. , Carmona-Novillo E. , Pirani F.
Published: March 2007

Weakly interacting molecules leading to collisional complexes, and to either stable or metastable
dimers, potentially play an important role in molecular and surface physics, in astrophysics, in atmospheric
photochemistry and physics, and climate. Accurate intermolecular potential energy surfaces for the major
components of the atmosphere, leading to the characterization of the O2‐O2, N2‐N2 and N2‐O2 dimers, have
been obtained from the analysis of scattering experiments from our laboratory, also exploiting where available
second virial coefficient data. A spherical harmonic expansion functional form describes the geometries
of the dimers and accounts for the relative contributions to the intermolecular interaction from components
of different nature. For O2‐O2, singlet, triplet and quintet surfaces are obtained accounting for the role of
spin‐spin coupling. The new surfaces allow the full characterization of structure and internal dynamics of
the clusters, whose bound states and eigenfunctions are obtained by exact quantum mechanics. Besides the
information on the nature of the bond, these results can be of use in modelling the role of dimers in air
and the calculated rotovibrational levels provide a guidance for the analysis of spectra, thus establishing the
ground for atmospheric monitorings. Reference is also briefly made to recent insight on the role of water.
Excited state structural relaxation relaxation of N‐(1‐anthryl)‐2,4,6‐trimethyl‐pyridinium cation
Authors: Khimich M. N. , Makarova N. I. , Knyazhansky M. I. , Uzhinov B. M.
Published: March 2007

The fluorescence spectrum of N‐(1‐anthryl)‐2,4,6‐trimethylpyridinium cation (1) has an anomalously
high Stokes′ shift. The fluorescence spectra of 1 in ethanol and butyronitrile are shifted to shortwavelength
region and fluorescence quantum yield increases as the temperature decreases. The fluorescence
rate constant of this compound changes considerably (6 times in ethanol and 15 times in butyronitrile) as
the temperature decreases from 293 K (relaxed state) to 77 K (mainly nonrelaxed state). It points out that at
these temperatures the fluorescence takes place from two species with different structures. It is concluded
that anomalously high fluorescence Stokes′ shift of 1 is caused by both solvent orientation relaxation and
excited state structural relaxation consisting in the mutual rotation of anthracene and pyridinium fragments
of the cation and resulting in the formation of a specie with different structure. The rates of these processes
are determined by the temperature‐dependent viscosity of the medium.
Photocatalytic degradation of natural organic matter: Kinetic considerations and light intensity dependence
Authors: Uyguner Ceyda Senem , Bekbolet Miray
Published: March 2007

The current study was conducted to investigate the photocatalytic degradation kinetics of humic
acid at different light intensities using commercial TiO2 powders. The pseudo first order kinetic model and
Langmuir‐Hinshelwood (L‐H) rate equation in modified forms were used to compare the photocatalytic activities
of TiO2 materials as a function of light intensity. Under constant irradiation conditions, the pseudo first
order reaction rates as well as L‐H rates were found to be decreasing in the following trend; Degussa P‐25,
Millennium PC‐500 and Millennium PC‐100. The pseudo first order rate constants showed the same decreasing
trend as the pseudo first order reaction rates while L‐H rate constants exhibited a light intensity related
change in the ordering of the photocatalysts. At the lowest light intensity, L‐H rate constants decreased as
follows: Millennium PC‐500 > Millennium PC‐100 > Degussa P‐25. However, increasing the light intensity
changed the order to; Millennium PC‐100 > Millennium PC‐500 > Degussa P‐25 revealing the significance
of the L‐H adsorption constant. Under constant irradiation conditions, ionic strength dependent changes in
the structure of humic acid did not alter degradation efficiency trend of the photocatalyst specimens and
they were ordered such as; Degussa P‐25 > Millennium PC‐500 > Hombikat UV‐100 > Millennium PC‐100 >
Merck. The results presented in this research also confirmed the effectiveness of Degussa P‐25 as a photocatalyst
for the degradation of humic acid.
Health effects, environmental impacts, and photochemical degradation of selected surfactants in water
Authors: Venhuis Sarah Hatfield , Mehrvar Mehrab
Published: March 2007

Surfactants are depended upon worldwide as cleaning agents. Their usage in such large quantities
means that their waste and the potential for pollution are high. Many studies have been done over the
last three decades encompassing treatment, alternatives to non‐biodegradable surfactants, and the environmental
impact. It has been found that although certain surfactants may not be directly toxic, when their
concentrations are high in soil, they can act as agents to release toxic pollutants such as polychlorinated
biphenyls (PCBs). The focus of this study is to review recent advances in the toxicology, the environmental
fate, and the treatment of selected surfactants. In addition, photolytic and photocatalytic degradation of
linear alkylbenzene sulfonate in water is presented.
Are dye‐sensitized nano‐structured solar cells stable? An overview of device testing and component analyses
Authors: Figgemeier Egbert , Hagfeldt Anders
Published: March 2007

The nano‐structured dye‐sensitized solar cell (DNSC) is considered as a promising technology
having the potential to significantly decrease the costs of solar energy. The breakthrough was achieved in
1991 with the demonstration of a DNSC system reaching more than 7% efficiency and after a decade of
intense research the commercialization is in reach. Besides efficiency, stability is equally important for the
step from research to the market. Therefore, the stability of such devices has been under close investigation
since the DNSC was presented. In this contribution we summarize the literature about device testing and
the attempts to understand the degradation mechanisms. Solar cells developed for energy production are
discussed as well as alternative systems for low power applications, e.g., DNSCs on plastic substrates. The
components (substrate, nano‐structured TiO2, dye, electrolyte, additive and counter electrode) are analyzed
towards their stability and how it affects the durability of the entire system. From this analysis, guidelines
for testing and improving the stability of the DNSC are deduced.
Synthesis and in vitro evaluation of dioxopyrrolopyrroles as potential low‐affinity fluorescent Ca2+ indicators
Authors: Avcıbaşi Nesibe , Smet Mario , Metten Bert , Dehaen Wim , De Schryver Frans C. , Bultynck Geert , Callewaert Geert , De Smedt Humbert , Missiaen Ludwig , Boens Noël
Published: March 2007

Three new low‐affinity fluorescent Ca2+ indicators excitable with visible light, namely
3‐phenyl‐6‐(4‐(3‐carboxymethoxy‐4‐(N,N‐dicarboxymethylamino)phenyl)phenyl)‐2,5‐dicarboxymethyl‐1,4‐
dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (DPP1), 3‐phenyl‐6‐(5‐(3‐carboxymethoxy‐4‐(N,N‐dicarboxymethylamino)
phenyl)thien‐2‐yl)‐2,5‐dicarboxymethyl‐1,4‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (DPP2) and 3‐
(thien‐2‐yl)‐6‐(5‐(3‐carboxymethoxy‐4‐(N,N‐dicarboxymethylamino)phenyl)thien‐2‐yl)‐2,5‐dicarboxymethyl‐
1,4‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (DPP3) have been synthesized and evaluated for their Ca2+ binding properties via fluorimetric titrations. The in vitro dissociation constant Kd measured at 21 ∘C in 100 mM KCl buffered solution, pH 7.05, for the Ca2+ –DPP1 complex is 10 μM; for Ca2+ –DPP2 and Ca2+ –DPP3 a Kd value of 20 μM is found. All three indicators form 1: 1 complexes with Ca2+. The fluorescence quantum yields of the uncomplexed forms of DPP1, DPP2 and DPP3 are 1.2 × 10−2, 3.4 × 10−2 and 3.6 × 10−2, respectively. After binding to Ca2+ these values increase to 4.8 × 10−2, 5.0 × 10−2 and 5.1 × 10−2, respectively.
Photochemical and thermal degradation of a naturally occurring dye used in artistic painting. A chromatographic, spectrophotometric and fluorimetric study on saffron
Authors: Vickackaite Vida , Romani Aldo , Pannacci Danilo , Favaro Gianna
Published: March 2007

Saffron is a yellow substance which is extracted from the stigmas of Crocus sativus L. and is
used in painting, cooking and medicine. In this paper six components (trans and cis crocins) with carotenoid
structures were separated from natural saffron by HPLC and were characterised by their absorption and
emission spectra. Photochemical and thermal processes which degrade the dye were also investigated. The
effect of light promoted the cis ⇄ trans isomerization, while the thermal effect detached the glycosyl moieties.
Photocapture of dynamic hydrogen‐bonded assemblies
Authors: McClenaghan Nathan D. , Bassani Dario M.
Published: March 2007

Recent advances in the continuing study of [2+2] photodimerization reactions in supramolecular,
non‐covalent systems are presented. The covalent photocapture of small dynamic assemblies which are
formed using weak hydrogen‐bonding interactions between two different complementary units, barbiturates
and melamines, is discussed. One unit serves as a photo‐inert supramolecular template capable of bringing
two photoactive units together using multiple hydrogen‐bonds. The second type of unit unites the corresponding,
complementary hydrogen‐bonding motif with a photoactive unit. Irradiation of the supramolecular
assemblies leads to photodimerization of adjacent units and generation of an imprinted site for the
template. Moieties which are adapted to participate in photodimerization reactions are styrene, cinnamate,
stilbene and fullerene units. The results are interpreted on the basis of topochemical reaction control.
Photochromic properties of six 5‐O‐n‐alkyl, 6′‐CN substituted spironaphthoxazines
Authors: Metelitsa A. V. , Micheau J. C. , Besugliy S. O. , Gaeva E. B. , Voloshin N. A. , Voloshina E. N. , Samat A. , Minkin V. I.
Published: March 2007

The photochromic properties of a series of six 5‐O‐n‐alkyl, 6′ ‐CN substituted spironaphthoxazines
has been investigated in toluene and methanol solution. The 6′ ‐CN and 5‐O‐n‐alkyl substitutions
lead to a bathochromic shift of the UV spectra of the closed forms. The λmax of the visible spectra of the open forms decrease with solvent polarity. Most of the photochromic parameters have been quantitatively
determined. Among them, photocoloration and photobleaching quantum yields and molar absorption coefficients
of the open forms have been derived from a numerical fitting of the photokinetic curves recorded
under continuous monochromatic irradiation. Results show that the photo‐steady‐state properties are relatively
independent of the 5‐O‐n‐alkyl chain length, but are more sensitive to the size of the indolinic nitrogen
substituent.
Surface photochemistry: Photodegradation study of pyrene adsorbed onto microcrystalline cellulose and silica
Authors: Oliveira A. S. , Ferreira L. F. Vieira , Da Silva J. P. , Moreira J. C.
Published: March 2007

Ground‐state diffuse reflectance, time resolved laser‐induced luminescence, diffuse reflectance
laser flash‐photolysis transient absorption and chromatographic techniques were used to elucidate the photodegradation
processes of pyrene adsorbed onto microcrystalline cellulose and silica. Ground‐state diffuse
reflectance showed that on both substrates low concentrations display absorption of pyrene monomers. At
high concentrations spectral changes attributed to aggregate formation were observed. Laser induced fluorescence
showed that pyrene onto microcrystalline cellulose mainly presents fluorescence from monomers,
while for silica, excimer‐like emission was observed from low surface loadings (≥0.5 μmol g−1). Transient absorption and photodegradation studies were performed at concentrations where mainly monomers exist.
On silica, pyrene presents transient absorption from its radical cation. On microcrystalline cellulose both
radical cation, radical anion and pyrene triplet‐triplet absorption were detected. Irradiation followed by chromatographic
analysis showed that pyrene decomposes on both substrates. For pyrene on microcrystalline
cellulose 1‐hydroxypyrene was the main identified photoproduct since in the absence of oxygen further oxidation
of 1‐hydroxypyrene was very slow. For pyrene on silica photodegradation was very efficient. Almost
no 1‐hydroxypyrene was detected since in the presence of oxygen it is quickly oxidized to other photooxidation
products. On both substrates, pyrene radical cation is the intermediate leading to photoproducts and
oxygen it is not involved in its formation.
Microcrystals of an organic fluorescent dye grown in the presence of various PAMAM dendrimers: Control of the morphology and optical properties
Authors: Bertorelle Franck , Al-Ali Fatima , Fery-Forgues Suzanne
Published: March 2007

Microcrystals of a fluorescent dye, 4‐n‐octylamino‐7‐nitrobenzoxadiazole, were prepared by the
reprecipitation method. Poly(amidoamine)dendrimers bearing anionic, cationic or neutral terminating groups
were used as additives in the recrystallization medium. They directed the formation of thin plates or spindlelike
microcrystals. The UV/vis absorption and emission properties were investigated on the microcrystal
suspensions.
Solid state photochromism of spiropyrans
Authors: Lukyanov B. S. , Metelitsa A. V. , Voloshin N. A. , Alexeenko Yu. S. , Lukyanova M. B. , Vasilyuk G. T. , Maskevich S. A. , Mukhanov E. L.
Published: March 2007

A series of spiropyrans possessing photochromic properties in solid state were investigated.
UV irradiation
(λmax = 365 nm) of the thin vacuum deposited spiropyran films results in conversion of
the colorless form to the photocolored one. The reaction is photochemically and thermally reversible. The
photochromic activity of the solid material and polystyrene matrix has been compared. Raman spectroscopy
has been used for studying the influence of metallic surface on the adsorbed spiropyran layers.
UV/VIS spectral properties of novel natural products from Turkish lichens
Authors: Posokhov Yevgen , Erten Şule , Koz Ömer , Anİl H. , Kİrmİzİgül Süheyla , Içli Sİddİk
Published: March 2007

UV/VIS spectral characteristics of three new biologically active natural products, isolated from
Turkish lichens, have been investigated in solvents of various polarity and proton donating ability. The
effect of the solvent on spectral characteristics has been estimated. Quantum chemical calculations with the
optimization of molecular geometry were done with the full‐valent semiempirical methods AM1 and PM3 for
conformational analysis and in order to discuss the charge distributions and dipole moments in the ground
and in the excited states.
Comparison of gel swelling under organic vapor and in organic solvent
Authors: Erdoğan M. , Pekcan Ö.
Published: March 2007

A Fast Transient Fluorescence Technique (FTRF) was employed for studying swelling of disc
shaped poly (methyl methacrylate) (PMMA) gels, which were prepared by free radical copolymerization of
methyl (methacrylate) (MMA) using various ethylene glycol dimethacrylate (EGDM) contents at 60  ∘C. Pyrene (P) was introduced as a fluorescence probe during polymerization. Swelling experiments were performed
by using P doped PMMA gels under chloroform vapor and in chloroform at room temperature. P lifetimes
in and out of the gel were measured from fluorescence decay traces during in-situ swelling experiments.
It was observed that P lifetimes in the gel decreased as swelling proceeds. An equation is derived for low
quenching efficiencies to interpret the behavior of P lifetimes during swelling. The Li‐Tanaka equation was
used to determine the cooperative, Dc diffusion coefficients for the gels made at various crosslinker contents.
It is observed that Dc values decrease as the crosslinker content is increased both in chloroform vapor and
in chloroform.
Photocatalytic membrane modules for drinking water purification in domestic and community appliances
Authors: Bellobono Ignazio Renato , Morazzoni Franca , Tozzi Paola Maria
Published: March 2007

In the present paper, the performance of a pilot plant for domestic use was investigated, able
to operate continuously, and in which tap water was fed (inorganic carbon IC: 81.6 ± 0.5 ppm; total organic
carbon TOC content: 1.52 ± 0.02 ppm). This plant produced 130 L/d of purified water. The tap water was first
subjected to a prefiltration by a membrane microfiltration unit, followed by filtration through a membrane
immobilising activated carbon, then through a reverse osmosis membrane, at a transmembrane pressure of
4 bar, and finally through a photocatalytic membrane unit, constituted by a metallic membrane, onto which
the semiconductor and its photopromoters were present as a 3–4 μm thick surface layer, directly produced
on the nanotechnologically treated surface of this membrane, irradiated at a power of 9.6 W in the range of
optical absorption by semiconductor. Efficiency of these operations was compared by carrying out parallel
experiments, using two other commercial plants (I and II), in which the photocatalytic treatment was not
provided for. All the three plants were able to soften the tap water down to 6–8ppm IC, but, as regards TOC,
(I) yielded a purified water still containing 1.12 ± 0.05 ppm of organic carbon, and (II) 0.908 ± 0.0095 ppm, while the TOC content of water purified in the pilot plant of present work was lowered down to 0.06 ± 0.02 ppm. In order to compare further efficiency of these plants, a simulated feed solution was treated, containing
3.05 ppm of humic acids, or 2.16 ppm of atrazine, or 4.23 ppm of symazine. Reverse osmosis, which was
present in all the three kind of plants examined, even if coupled with active carbon adsorption, was not able
to remove entirely contamination due to organic micropollutants. This goal, on the contrary, was successfully
achieved by the plant fitted with the photocatalytic membrane unit, particularly by considering that this
plant showed substantially the same abatement efficiencies of plants (I) and (II), if the photocatalytic unit
was switched off.
Photo reduction of CO2 to methanol via TiO2 photocatalyst
Authors: Wu Jeffrey C. S. , Lin Hung-Ming
Published: March 2007

Greenhouse gas such as CO2 is the primary cause of global warming. Alternative energy source
should be provided without producing more CO2, such as solar energy. One of the best routes to remedy
CO2 is to transform it to hydrocarbons using photo reduction. In our study, CO2 was photocatalytically reduced to produce methanol using a Hg lamp with wavelength 365 nm in a steady‐state optical‐fiber photo
reactor. The optical‐fiber photo reactor, comprised of near 120 Cu/TiO2‐coated fibers, was designed and
assembled to transmit and spread light uniformly inside reactor. TiO2 film was coated on optical fiber using
dip‐coating method. Titania and Cu‐loaded solutions were prepared by a thermal hydrolysis method. The
thickness of Cu/TiO2 film was 53 nm and consisted of very fine spherical particle with diameter of near
14 nm. The XRD spectra indicated the anatase phase of all TiO2 and Cu/TiO2 films. The wavelength of
absorption edge was on 367 nm, equivalent to near 3.3 eV. Most active Cu species on TiO2 surface were Cu2O clusters, and played an important role for the formation of methanol. The methanol yield increased with
UV irradiative intensity. Photo activity increased with increasing Cu loadings. Maximum methanol rate was
0.45 μmole/g‐cat•hr using 1.2 wt%‐Cu/TiO2 catalyst under 16 W / cm2 irradiation, 1.3 bar pressure of CO2, and 5000 seconds mean residence time. Higher than 1.2 wt% Cu loading gave less rate of methanol yield
because of the masking effect of Cu2O clusters on the surface of TiO2.
Taming fluorescent dyes with cucurbituril
Authors: Nau Werner M. , Mohanty Jyotirmayee
Published: March 2007

The potential of the supramolecular host molecule cucurbit[7]uril to serve as a stabilizing additive
and enhancement agent was investigated for the following dyes in aqueous solution: rhodamine 6G,
rhodamine 123, tetramethylrhodamine, cresyl violet, fluorescein, coumarin 102, pyronin B, pyronin Y, two
cyanine 5 and one cyanine 3 derivative, and IR140 as well as IR144. For most cationic dyes photostabilization
was established, and a pronounced thermal stabilization due to deaggregation and solubilization
was observed for the xanthene dyes. The advantageous effects are attributed to the formation of inclusion
complexes with different photophysical and photochemical properties. The complexation is accompanied by
spectral shifts characteristic for the inclusion in a less polar environment, while the fluorescence quantum
yields as well as the brightness show an increase, with few exceptions. As a consequence of the low polarizability
inside the cucurbituril cavity, the fluorescence lifetimes of the included dyes increase substantially
and systematically. Applications of the new photostabilizing additive for dye lasers, for prolonged storage
of dye solutions, in scanning confocal microscopy, and fluorescence correlation spectroscopy are discussed.
One‐step flame synthesis of SnO2 / TiO2 composite nanoparticles for photocatalytic applications
Authors: Akurati Kranthi K. , Vital Andri , Hany Roland , Bommer Bastian , Graule Thomas , Winterer Markus
Published: March 2007

SnO2 / TiO2 composite nanoparticles have been synthesized in a single‐step by feeding evaporated
precursor mixtures into an atmospheric pressure diffusion flame. Particles with controlled Ti: Sn ratios
were produced at various flow rates of oxygen, and the resulting powders were characterized by BET surface
area analysis, XRD, TEM, EDAX and UV‐Vis spectroscopy. For the lowest concentration (3.4 mol %) of SnO2 employed in this study anatase phase of TiO2 is stabilized, while segregation of SnO2 is seen at medium (6.9 to 12.4 mol %) and high concentrations (20.3 mol %). Though the equilibrium phase diagram predicts complete
solubility of one oxide in another at all compositions, segregation of SnO2 phase is observed which is explained by the usage of diffusion flame in the present study. The particle formation mechanism of
SnO2 / TiO2 composites is proposed basing on the single component aerosol formation. Photocatalytic activity
of the composite particles is tested for the degradation of methylene blue and is compared with pure
TiO2 synthesized under similar conditions. Improved photocatalytic activity of the composite particles is
attributed to the stabilized anatase phase and better charge separation due to the coupling of TiO2 and SnO2 within the composite nanoparticles.
The effect of surface hydroxyl groups on the adsorption properties of nanocrystalline TiO2 films
Authors: Vuk Angela Šurca , Ješe Robi , Orel Boris , Dražč Goran
Published: March 2007

Nanocrystalline TiO2/Brij and TiO2/Pluronic films were prepared with a view to their application
in electrochromic and Grätzel cells and examination of their photocatalytic effect. The films were prepared
from titanium (IV) isopropoxide with the addition of Brij 56 or Pluronic F127. Films were deposited by
dip‐coating, thermally treated at 500 ∘C and analysed by XRD, TEM and IR analysis. XRD and TEM analyses
revealed the presence of anatase nanoparticles embedded in the amorphous phase. The presence of the latter
was also confirmed by a broad high‐frequency shoulder of the Ti‐O stretching mode at 436 cm−1 that was found for films prepared with both kinds of surfactants. Addition of surfactants decreased the size of the
particles and increased the surface roughness, and consequently in IR spectra the surface hydroxyl Ti‐OH
modes appear between 3800 and 3600 cm−1. IR measurements also revealed that TiO2 films with surfactants have a higher photocatalytic effect which was tested for stearic acid by following the integral intensity of
C‐H and C=O IR bands.
Effects of pilot‐plant photochemical pre‐treatment (UV/H2O2) on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS)
Authors: Mehrvar Mehrab , Tabrizi Gelareh Bankian , Abdel-Jabbar Nabil
Published: March 2007

The effects of the photochemical pre‐treatment by using a pilot‐plant UV/H2O2 process on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS) were studied. It was observed that the
photochemical pre‐treatment of the LAS solutions by UV‐254/H2O2 increased the biodegradability of LAS
solutions. Aqueous solutions with higher concentrations of LAS (> 100 mg/L) were non‐biodegradable. The
ratio of BOD5/COD of the pre‐treated LAS solutions was increased, indicating that the pre‐treated LAS solutions
were more biodegradable. This ratio was improved as the LAS solutions were more pre‐treated. Also,
the biodegradability factor for the pre‐treated LAS solutions was increased as the time of the photochemical
pre‐treatment was increased.
Photocatalytic efficiency of titanium dioxide immobilized on PVP/AAc hydrogel membranes: A comparative study for safe disposal of wastewater of Remazol Red RB‐133 textile dye
Authors: Hafez Hoda S. , Ali A. El-Hag , Abdel-Mottaleb M. S. A.
Published: March 2007

The paper reports on the photocatalytic efficiency of TiO2 nanoparticles immobilized on
polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogels, which are prepared by means of γ‐rays induced homo‐ and copolymerization. The efficiency of immobilized photocatalyst is tested on a commercial
textile dye namely Remazol Red RB‐133. The results are compared with photocatalytic efficiencies of
different types of non supported TiO2 photocatalysts such as aqueous slurries of colloidal TiO2 prepared by sol‐gel technique, and commercially available Degussa P25. Although less efficient than nonsupported
ones, the hydrogel supported TiO2 photocatalyst has the practical advantages of easy separation and removal
from the reactors. This makes it a viable technique for the safe disposal of textile wastewater into the
water streams.
Photochemical and photobiological properties of furocoumarins and homologues drugs
Authors: Bordin F.
Published: March 2007

Furocoumarins are natural photosensitizing drugs used in PUVA photochemotherapy and in
photopheresis. Their therapeutic effectiveness is connected to the lesions they induce to various cell components,
membranes, ribosomes, mitochondria, and in particular to DNA, damaged by formation of monofunctional
adducts and of inter‐strand cross‐links (ISC). ISC represent a severe damage, mainly correlated to the
main side effects observed in photochemotherapy, skin phototoxicity and genotoxicity. Searching for new
monofunctional derivatives, two tetramethylfuroquinolinones, 1,4,6,8‐tetramethyl‐2H‐furo[2,3‐h]quinolin‐2‐
one (FQ) and 4,6,8,9‐tetramethyl‐2H‐furo[2,3‐h]‐quinolin‐2‐one (HFQ) were studied. Both compounds are very
active; however while FQ produced many chromosomal aberrations and strong skin erythemas, HFQ practically
did not induce such side effects. FQ and HFQ formed high levels of monoadducts but no ISC in DNA,
but both provoked many DNA‐protein cross‐links (DPC). FQ induced these lesions by a biphotonic reaction:
at first a furan‐side monoadduct is formed, which is then converted into a DPC; thus the FQ molecule seemed
to form the bridge between DNA and proteins. HFQ formed DPC by a single step (DPC at zero length, like
UVC). For these features, HFQ appears to be the first molecule belonging to a new class of active but not
phototoxic drugs for photomedicine.
Molecular mechanisms of photosensitization induced by drugs XIV: Two different behaviours in the photochemistry and photosensitization of antibacterials containing a fluoroquinolone like chromophore
Authors: Guidi G. De , Giuffrida S. , Monti S. , Pisu P. S. , Sortino S. , Costanzo L. L.
Published: March 2007

This paper deals with the photosensitizing activity of FLQs towards two different biosubstrates,
membrane and DNA. The in vitro phototoxic activity of these drugs vs. DNA presents peculiar features
with respect to that vs. membranes, probably due to a specific binding of the drugs to the double helix
and to the operativeness of different photosensitization mechanisms with the two types of biosubstrates.
A description of the UVA photochemistry and the photosensitizing properties of two significant examples
in the FLQ family is reported. The investigated compounds are Enoxacin, 1‐ethyl‐6‐fluoro‐1,4‐dihydro‐4‐
oxo‐7‐[1‐piperazinyl]‐1,8‐naphtyridine‐3‐carboxilic acid and Rufloxacin, 9‐fluoro‐2,3‐dihydro‐10‐4´‐methyl‐
1´‐piperazinyl‐7‐oxo‐7H‐pyrido[1, 2, 3 − de]‐1,4‐benzothiazine‐6‐carboxylic acid.
On the absorption and emission properties of three newnon‐steroidal anti‐inflammatory drugs‐β‐cyclodextrinhost‐guest inclusion complexes: differentiatedsensitivity to the microenvironmentupon light excitation
Authors: Sortino S. , Guidi G. De , Fazio S. , Giuffrida S. , Salemi M. G. , Monti S.
Published: March 2007

The effects of β‐cyclodextrin (β‐CD) complexation on the absorption and emission properties of
the non‐steroidal anti‐inflammatory drugs tolmetin (TM), diflunisal (DF), and fenbufen (FB) have been investigated.
The absorption spectra of all these compounds are only slightly affected by the addition of β‐CD. In
contrast, the emission properties were markedly influenced by CD complexation and in a different manner
for the three compounds due to a differentiated sensitivity of the excited drugs to the microenvironment.
The complexes are all characterised by a 1: 1 stoichiometry and two different inclusion geometries for TM‐
β‐CD complexes have been observed. Induced circular dichroism (icd) is observed due to the interaction of
the compounds with the CD chiral cavity. The icd spectra are characterized by maxima well corresponding
to those of the absorption spectra. A nonlinear analysis of the dependence of the icd signal magnitude on
the CD concentration provided association constants values Kass = 1400 ± 100M−1, and 2600 ± 150M−1 for TM, DF, and FB respectively.
Intermediates of reversible photochemistry of phycoerythrocyanin α from Mastigocladuslaminosus probed by low temperature absorptionand circular dichroism spectroscopy
Authors: Zhao Kai-Hong , Scheer Hugo
Published: March 2007

The reversible photochemistry of the α‐subunit of phycoerythrocyanin (α‐PEC) has been measured
by low temperature absorption and circular dichroism in the range of 125K to 295 K. Below 185 K, the
photochemistry is nearly silent; above 205 K, the photochemistry increases gradually without an indication
of intermediates, and between 185 to 205K spectral changes in absorption and circular dichroism indicate
an intermediate and/or changes in the interaction(s) between the chromophore and its environment.
Phototransformations of non‐toxic antioxidants, the derivatives of 1,2‐dihydroquinolines, in homogeneous and micellar solutions
Authors: Nekipelova T. D.
Published: March 2007

Reactions of transient species photogenerated from 6‐R‐2,2,4‐trimethyl‐1,2‐dihydroquinolines
(TMDQ) are very sensitive to medium variation. In anhydrous organic solvents, aminyl radicals were generated.
They decay in the reaction of dimerization with the second‐order rate constant decreasing in a row
heptane>benzene>2‐propanol. When passing from organic solvents to water, methanol, and water‐alcohol
solutions, the kinetics and the direction of the reaction crucially change. As a result of the photolysis, the
product of the addition of a solvent to the double bond of heterocycle, 4‐hydroxy‐ or 4‐methoxy‐6‐R‐2,2,4‐
tetramethyl‐1,2,3,4‐tetrahydroquinoline is formed in water and methanol, respectively. The transformation
is a complex reaction, and the formation of excited transient species is followed by a sequence of first‐order
and pseudo‐first‐order reactions. Unlike the photolysis in anhydrous organic solvents, the reaction in water
and methanol does not involve aminyl radicals. In aqueous solutions, the first‐order rate constants for the
decay of transient species are higher in acidic and neutral solutions. At the pH close to pKa of the transient
species, it drops, indicating that the neutral form is less reactive. The same product is formed over the whole
range of pH. For the anionic surfactant (SDS) in acidic and alkaline solutions, the apparent rate constant in
the micellar solutions is lower than that in the aqueous (negative micellar catalysis). At the medium pH, a
positive micellar catalysis is observed, and the rate constant of the decay depends linearly on the concentration
of TMDQ in the micelles, indicative of the direct reaction between TMDQ and the cationic transient
species.
Phototransformation of halogenoaromatic derivatives in aqueous solution
Authors: Boule P. , Othmen K. , Richard C. , Szczepanik B. , Grabner G.
Published: March 2007

The photochemical behaviour of monohalogeno‐phenols and ‐anilines is highly dependent on
the position of the halogen on the ring, but most often it is not significantly influenced by the nature of
the halogen (Cl, Br, F). Photohydrolysis is the main reaction observed with 3‐halogenated and it is almost
specific. With 2‐halogenated, photohydrolysis and photocontraction of the ring compete, the latter being
very efficient with 2‐halogeno‐phenolates.The photochemical behaviour of 4‐halogeno‐phenols and ‐anilines is more complex. It depends on both
concentration and oxygenation. It was rationalized when it was experimentally proved by laser flash photolysis
that the first step is the formation of a carbene (in the cationic form in the case of 4‐halogenoaniline).
ρ‐Benzoquinone is the product of photooxidation of 4‐halogenophenols, whereas the photooxidation of
4‐chloroaniline leads to 4‐amino‐4´‐chlorodiphenylamine.Chlorohydroquinone behaves differently, the formation of the main photoproducts involving a radical
mechanism.With dihalogenoanilines photohydrolysis is initially almost quantitative whatever the position of halogen
atom on the ring. It occurs more easily in meta than in ortho position and in ortho than in para position. In
the case of 2,4‐ and 2,6‐dichloroanilines aminophenoxazones are formed as secondary photoproducts. This
reaction involves the intermediate formation of o‐benzoquinone monoimine.
Several halogenoaromatic herbicides were also studied (bromoxynil, chlorpropham, propanil, diuron, linuron,
chlorbromuron, MCPA). The most frequent reaction is photohydrolysis. However some other reactions
such as photoreduction and photo‐demethoxylation were observed. In some cases a wavelength effect was
observed particularly with MCPA and halogenophenylureas.
Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide
Authors: Ledakowicz Stanislaw , Miller Jacek S. , Olejnik Dorota
Published: March 2007

The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene, chrysene and
fluorene in aqueous solution using advanced oxidation process H2O2/UV was investigated. The influence of
pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The
oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentration
(ca. 0.01 M). The degradation of benzo[a]pyrene and chrysene follows radical reaction, for fluorene the
mechanism is not clear. The rate constants of the hydroxyl radicals and selected PAHs reaction were found
to be 2.53 × 1010, 9.82 × 109 and 2.77 × 109M−1S−1 for benzo[a]pyrene, chrysene and fluorene, respectively