Oktakıs (alkiltiyo)-substitue ftasoliyaninlerin sentezi ve Ag(I), Pd(II) iyonlarıyla etkileşimi
Synthesis of octakis (alklythia)-substituted phthalociyanines and their interactions with Ag(I) and Pd(II) ions
Yazar: AYŞE GÜL GÜREK
Danışman: PROF.DR. ÖZER BEKAROĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü
Derece: Yüksek Lisans, 1994
Konu: Kimya = Chemistry
Dizin: Ftalosiyaninler = Phthalocyanines ; Gümüş = Silver ; Kurşun = Lead ; Sıvı kristaller = Liquid crystals ; İyon = Ion

Özet:
ÖZET Ftalosiyaninler genellikle ftalonitril, ftalikanhidrit, ftalimid veya bunların substitüsyon ürünleri ile metal tuzları arasındaki reaksiyonlardan elde edilebilirler. Ftalosiyaninler genellikle güç çözünen bileşiklerdir. Ftalosiyanin kimyasındaki önemli bir hedef de çözünür ürünler elde etmektir. Çözünürlük, periferal olarak hacimli substitüentler (örneğin; -t-butil, -C^H^, -OC12H15) veya polar gruplar (örneğin; -S03Na, -NR3+) ilavesiyle başanlabilmektedir. Makrohalkalarda ftalosiyaninlerin çözünürlüğünü arttırmaktadır. Taç eter, monoaza ve tetra makro halkaları içeren ftalosiyaninlerin sentezi ve incelenmesi grubumuz tarafından yapılan çalışmaların büyük bir bölümünü oluşturmaktadır. Bu çalışmada 4,5-dikloro-l,2 disiyano benzenden yola çıkarak 4,5-bis (heksiltiyo)- (I) ve 4,5-bis (dodesiltiyo)-l,2 disyano benzenQa) türevleri elde edilmiştir. 4,5-bis (alkiltiyo) fitalonitrillerden (I, la) DBU ile metalsiz ve susuz metal tuzlanyla [NiC^, CuCl, CoCl2, Zn(OAc)2] bu tuzlara karşı gelen, periferal pozisyonlarda sekiz alkiltiyo- grubu taşıyan metalli ftalosiyaninler sentezlenmiştir. Bu ftalosiyaninlerin ftalosiyanin/metal oranı 1:4 olacak şekilde Ag ve Pd tuzlan ile kompleksleri elde edilmiştir. Kompleksleşme reaksiyonlarının, spektrofotokimyasal incelemeleri, Ag ile kompleksleşmenin agregasyona neden olmasına rağmen Pd tuzunun ilavesiyle agregasyonun yok olduğu ve 720 nm'de yeni bir Q bandının oluştuğunu göstermektedir. Elde edilen yeni maddelerin yapısı Elementel analiz, İR, UV-VIS, atomik absorpsiyon ve NMR'la aydınlatılmıştır. -v-

Abstract:
SUMMARY SYNTHESIS OF OCTAKIS (ALKLYTHIA)-SUBSTITUTED PHTHALOCIYANINES AND THEIR INTERACTIONS WITH Ag(I) AND Pd(II) IONS The special nature of the macrocycle phthalocyanine and its metal complexes have been known for about 60 years. Since then the unique physical and chemical properties of this class of coordination compounds have been exploited from both the practical as well as the theoretical point of view. Thus, metallophthalocyanines have important uses as commercial dyes, optical and electrical materials, and catalysts. In recent times compelling reason to study the detailed coordination chemistry of metallophthalocyanines has arisen. The great activity in bioinorganic chemistry of metallophthalocyanines has arisen. The great activity in bioinorganic chemistry has led to veritable avalanche of work on metalloporphyrins and other naturally occurring macrocylic coordination compounds. Thus the metallophthalocyanines are being examined in earnest and their properties compared to those of the porphyrin complexes in hopes of arriving at an understanding of how the naturally occurring macrocyclic porphyrin ligand affects the properties of the metal [3]. Unsubstituted and substituted phthalocyanines are widely used as pigment and dyes. Various other properties for new applications were investigated more recently: photosentization in solution, photodynamic activity in the photodynamic cancer therapy, electrocatalysts for the dioxygen reduction in fuel cell reactions, photoreductions or photooxidations in photoelectrochemical cells, electrochromic processes as thin films, materials for electrophotography, charge seperation in photovoltaic cells, optical information storage systems, catalysts, for mercaptan oxidations and use as sensors. For most of these applications, phthalocyanines bearing substituents had to be prepared in order to improve the above mentioned properties and to enhance the solubility or to perform coupling to -VI- iother reagents like polymers [23]. The rich coordination chemistry of phthalocyanine complexes has promoted the researches to "tailor" specific products with certain properties which are required by high technology applications. The two variables are the central metal ion and the peripheral substituents: when the possibility of inserting great number of different metal ions into phthalocyanine core is combined with the oppurtunity of unlimited number type of substituents, the possibility of obtaining novel products is infinite. Our primary aim has been the synthesis of new phthalocyanines with various functional groups and/or macrocycles. Amoung these we may cite the N and O containig functionalities such as crown ethers[6,7,8,12], aza-crown ethers[14,15], diazatrioxa-[24] or tetraaza macrocyles [16,17,18]. Substitution with four or eight long chain alkoxy groups has been also frequently encountered [22]. The consequence of these substituents have been enhanced solubility, alkali or transition metal ion binding, ion channel and discotic mesophase formation [21]. Pure substituted phthalocyanines are prepared by cylotetramerization of substituted 1,2-dicyanobenzenes or l,3-diimino-lH-isoindoles[l,2,4]. If monosubstituted 1,2-dicyanobenzenes are employed, tetrasubstituted phthalocyanines with the disadvantage of a mixture of place isomers are obtained. 4,5-disubstituted derivates as starting materials lead to 2,3,9,10,16,17, 23,24-identically substituted phthalocyanines. The two substituents of the 1,2- dicyanobenzenes had to be introduced at a precursor, and a longer preparative route is necessary for 2,3,9,10,16,17,23,24-octasubstituted phthalocyanines. 1,4,8, 11,15,18,22,25-octaalkoxy substituted phthalocyanines are obtained by alkylation of 2,3-dicyanobenzenes followed by their conversion to phthalocyanines [38]. Phthalocyanines substituted with thia-donors are rather few [26,27]. Also a small number of recent patents and proceedings describe the use of these types of compounds as DR. absorbers [28,29,30]. The shift of the high intensity Q bands to the longer wavelengths is a common feature of these compounds. We have recently reported the synthesis of metal-free and Ni(II) phthalocyanines with four long chain alkylthioether substituents and their complexation through thia-donor groups with Ag(I) and Pd(II) ions[31]. While the tetrasubstituted phthalocyanines obtained from 4-substituted-phthalonitriles are a mixture of o-bis(thioether)s with metal ions is naturally expected to be -vu-different than the mono-derivatives.In the present work, phthalocyanines with eight peripheral alkylthioether substituents have been accomplished and their complexes with the same metal ions are investigated. 4,5-Dichloro-l,2-dicyanobenzene was used recently to prepare 4,5- disubstituted-phthalonitrile derivatives through base-catalysed nucleophilic aromatic displacement reaction[23,28,29]. The same reaction route was applied to prepare 4,5-bis(hexylthio)- and 4,5-bis(dodecylthio)-l,2-dicyanobenzene (la and lb) from the corresponding n-alkylthiols and 4,5-dichloro-l-2- dicyanobenzene (Scheme 1). The reactions were carried out in dimethylsulfoxide at room temperature with a pretty high yield ( _ 80%). 2R-SH+CYVN ' ??RSHCN 2 R SH ClJ^AcN RS^^CN ?Pc la R=-C6H13 1_b R="Ci2^?^ Scheme l.(i) I^CO^ (CH3)2SO Cyclotetramerization of the phthalonitrile derivativeQa) into metal-free phthalocyanine(2) was accomplished in n-pentanol in the presence of a strong base (DBU) at reflux temperature[23,32] (Figure). The metal-phthalocyanines (3-6) were obtained by using the anhydrous metal salts (NiCl^ CuCl, CoCl2 and Zn(OAc)2). Column chromatography with silicagel was the method to obtain the pure product from the reaction mixture. The intensely green colored products are very soluble in a number solvents such as chloroform, dichloromethane, carbon tetrachloride, benzene, THF, petroleum ether, etc. The solubility of 3 in dichloromethane as determined spectrophotometrically was 7.8x10 mol/dm which was even higher than the other soluble phthalocyanines such as tetrakis (crown ether)- or tetradodecylthio-substituted ones[31]. The interaction of silver(I) and palladium(II) ions with the thioether groups of the phthalocyanines gave products with phthalocyanine: metal ratio of 1:4. They can be easily differentiated from the free phthalocyanines by their bluish tone and lesser solubility in common solvents, especially in the case of Pd derivatives. -vui-1 13 Elemental analyses, IR, H and C NMR and UV-VIS spectra confirm the proposed structures of the compounds. In the IR spectra of lâ and Ife, the intense absorption bands at 2240 and 2220 cm respectively, correspond to the C=N groups, which disappear after their conversion to the phthalocyanines. The N-H groups in the inner core of metal-free phthalocyanine 2 cause the absorption at 3300 cm" ; these protons are also very well characterized by H NMR spectrum which shows their chemical shift at -3.21 ppm as a result of the 18 7i -electron system of phthalocyanine ring[6-8]. A distinct difference encountered in the H NMR spectra of the phthalocyanines 2-£ when compared with our previous works with macrocycle-substituted ones is the sharp peaks which show the lesser tendency of aggregation in 2-Ğ even in the concentration used for NMR measurements[12-15, 24]. The C NMR spectral data given in Table 5.2 are also in accordance with the expected structures. Figure 1. Octakis(alklythia)-substitüted Phthalocyanines and Their Complexes -IX-Octakis(alkythio)-substituted phthalocyanines 2-6 show intense Q absorption bands above 700 nm (Table 5.3). When compared with octakis(alkyl- or alkoxy)- substituted ones, the shift of this intense band is especially important and will receive further attention for various near IR applications. The characteristic Q- band has been considered as a probe in discussing the self-assembling features of phthalocyanines in solution[4]. While the monomelic species with D2h symmetry (i.e. metal-free derivatives) shows two intense absorptions of comparable intensity around 700 nm, those having D4h symmetry give only a single band in this region. Any increase in the concentration results with the aggregation of phthalocyanine molecules which is clearly observed by a blue shift of Q band with some decrease in the intensity. It has been also concluded that aggregation is enhanced with solvent polarity and with the presence of aliphatic side chains[6-8,20,39,40]. When the electronic spectra of the phthalocyanines 2-6 were investigated, some pecularities could be easily observed. The two intense Q bands of the metal-free derivative 2 were somewhat distorted leading to a third band of medium intensity around 670 nm. The Ni(II) phthalocyanine showed a completely novel behaviour in the lower energy side of the spectrum: While the Q band was appeared as an intense peak at 702 nm with a shoulder around 675 nm corresponding to the monomelic and aggregated forms in chloroform or THF, its spectra in the solvents of lower dielectric constant such as CC14 or benzene were completely different and is contradictory to the expectations. Here we observed an intense Q band splitted into a doublet at 669 and 700 nm in these apolar solvents. These two absorptions cannot be attributed to the monomelic and aggregated species, while the solvents of low polarity are known lead to monomers especially in the concentrations studied (10" mol/dm ). Also the shape of the Q band region of 3 in CC14 is completely different than those encountered for many soluble metallo-phthalocyanines which have a broad absorption for the dimers, trimers, etc. in the higher energy side with a satellite band at higher wavelengths for the monomers[41, 42]. Since similar spectra have been obtained in the cases of both 3_â with C6 and 3& with C12 substituents, alkyl chain length should not be expected to have any contribution. In order to test the effect of central metal ion on the changes in Q band, the spectra of all phthalocyanines 3-6 in these solvents have been carefully investigated: It has been observed that in addition to Ni(II) phthalocyanine (3) similar splitting of the Q band, but to a- lesser extent, has been occuring only for the Cu(II) derivative 4. This result might be interpreted as the formation of some intermolecular interactions between the central metal ion of one molecule with the thiaether groups of another one.1 13 Elemental analyses, IR, H and C NMR and UV-VIS spectra confirm the proposed structures of the compounds. In the IR spectra of lâ and Ife, the intense absorption bands at 2240 and 2220 cm respectively, correspond to the C=N groups, which disappear after their conversion to the phthalocyanines. The N-H groups in the inner core of metal-free phthalocyanine 2 cause the absorption at 3300 cm" ; these protons are also very well characterized by H NMR spectrum which shows their chemical shift at -3.21 ppm as a result of the 18 7i -electron system of phthalocyanine ring[6-8]. A distinct difference encountered in the H NMR spectra of the phthalocyanines 2-£ when compared with our previous works with macrocycle-substituted ones is the sharp peaks which show the lesser tendency of aggregation in 2-Ğ even in the concentration used for NMR measurements[12-15, 24]. The C NMR spectral data given in Table 5.2 are also in accordance with the expected structures. Figure 1. Octakis(alklythia)-substitüted Phthalocyanines and Their Complexes -IX-In conclusion, the high solubility and red-shift of the Q-band in the octakis (alkylthio) substituted phthalocyanines should be mentioned along with the donor capabilities of the thia groups. The mesogenic properties as well as their electrical conductivity will be investigated in due course. -xn-