bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progress in the Development of Methods for Asymmetric Organic Synthesis
Authors: Schultz Arthur G. 
Published: May 2015

AbstractMethods for the enantioselective synthesis of chiral cyclohexane derivatives from aromatic carboxylic acids are presented. Birch reduction‐alkylation of chiral benzamides of type 1 occur with high diastereose‐lectivities to give 1,4‐cyclohexadiene derivatives with quaternary centers located at C(6). Early applications of this chemistry provided target structures with a quaternary center derived from C(1) of the starting benzoic acid derivative. Herein are described 1) the development of a more versatile Birch reduction‐alkylation, 2) a practical “asymmetric linkage” between aromatic carboxylic acids and chiral acyclic structures, and 3) asymmetric syntheses of unnatural alkaloids; applications to opiate receptor pharmacology.
Diels‐Alder Reactions of 5,8‐Ethano‐5,8‐dihydro‐1,4‐naphthoquinone with Cyclic Dienes
Authors: Chou Teh‐Chang , Liou Jing‐Ann , Lin Cheng‐Tung 
Published: May 2015

AbstractDiels‐Alder cycloadditions of 1,3‐cyclohexadiene and cyclopentadiene to π ‐facially dissymmetric 5,8‐ethano‐5,8‐dihydro‐1,4‐naphtboquinone (1) were examined. The stereochemical outcome of the reactions, determined by a combination of chemical and spectral methods, indicates that addition of cyclic dienes to 1 occurs preferentially at the face syn to the etheno‐bridge of 1. Cycloadducts 7a/7b and 8a/8b obtained from Diels‐Alder reactions of 1 with cyclopentadiene and 1,3‐cyclohexadiene undergo [2+2]‐photocyclization to give caged compounds 9a/9b and 10a/10b, respectively. Stereoselective reduction of the enedione double bond in 7a/7b and 8a/8b with aqueous TiCl3 in acetone affords cis‐bis‐bicyclic ring‐fused 1,4‐cyclo‐hexadiones 11a/11b, and 12a/12b, respectively.
Synthesis of 1‐Methyl‐2,5‐dimethylene‐2,5‐dihydropyrrole by the Flash Vacuum Pyrolysis of N‐(1,5‐Dimethyl‐2‐pyrryl)methyl Benzamide
Authors: Tseng Pen‐Wen , Chou Chin‐Hsing 
Published: May 2015

AbstractPyrolysis of N‐(1,5‐dimethyl‐2‐pyrryl)methyl benzamide (7) gaved a 1:1 ratio of 1‐methyl‐2,5‐dimethylene‐2,5‐dihydropyrrole (4b) and 1,2‐dimetbylpyrrole (10) as the primary pyrolysis products in 88% total yield. The reactive compound 4b was detected with low‐temperature 1H NMR spectroscopy. Upon warming, 4b reacted rapidly with 10 to give one‐on‐one, two‐on‐one and three‐on‐one adducts, 11, 12 and 13, respectively.
Synthesis of β‐Disubstituted Enones from Ynones. An Alternative Route to 1,4‐Addition of Cuprate to the Ynone System
Authors: Luo Fen‐Tair , Hsieh Li‐Chen , Fwu Shiang‐Long , Hwang Wen‐Shu 
Published: May 2015

AbstractA one‐pot reaction of 4‐phenyl‐3‐butyn‐2‐one with hydrogen iodide generated in situ gave a hydroiodinated product that underwent cross coupling with organozinc compounds in the presence of palladium catalyst to provide a simple preparation of 4‐disubstituted‐3‐alken‐2‐ones in fair to good yields.
Bicyclo[3.2.1]octenones As Building Blocks in Natural Products Synthesis (III). Total Synthesis of (±)‐10‐Deoxygeniposide Aglucone
Authors: Hsu Lung‐Fu , Chang Nein‐Chen 
Published: May 2015

AbstractThe title compound was synthesized from bicyclo[3.2.1]octenone 1 in six steps and in overall yield 59%. Photochemical rearrangement of β,γ‐unsaturated enone 1 is the key step.
Effect of Orbital Overlap in Thermal Reverse Homo‐Diels‐Alder Reaction and Intramolecular Reverse Ene Reaction
Authors: Tsai Tzeng‐Guang , Yu Chin‐Hui 
Published: May 2015

AbstractSemiempirical calculations of activation energies confirm the importance of orbital overlap effect on thermal reverse homo‐Diels‐Alder reactions and intramolecular reverse ene reactions. Computations of the transition states of cis‐3,6‐dimethyl‐3,6‐dihdropyridazine, 2,5‐dimethyl‐3,4‐diaza bicyclo[4.1.0]hept‐3‐ene, 2,5‐dimethyl‐3,4‐diaza bicyclo[4.2.0]oct‐3‐ene and (cis‐2(S)‐(2(S)‐isopropyl‐1‐d3)‐1(S)‐(1(E)‐propenyl‐2‐d)cyclopropane indicate that activation energies are considerably decreased when optimal overlap is accomplished. The orbital overlap effect overcomes the steric effect in intramolecular reverse ene reaction of compounds such as (cis‐3‐R‐2(S)‐(2(S)‐isopropyl‐1‐d3)‐1(S)‐(1(E)‐propenyl‐2‐d)cycIopropane in which R is a chlorine atom or a methyl group.
Analysis of Vibration‐rotational Spectra of BiH
Authors: Ogilvie J. F. 
Published: May 2015

AbstractAnalysis of measurements of vibration‐rotational transitions of 209Bi1H and 209Bi2H in electronic ground state × 0+ yielded values of coefficients of radial functions that represent the intemuclear potential energy and adiabatic and nonadiabatic rotational effects of the hydrogen atomic centre. Both these effects have exceptionally large magnitudes, tentatively attributed in part to interaction with nearby electronically excited state A 1. The maximum range of validity of radial functions of BiH is 1.49 ≤ R/10−10 m ≤ 2.4; the equilibrium intemuclear distance Re is (1.8041955 ± 0.00000186) × 10–10 m.
Structure and Stability of XNP and NPX, X = H+, CH3+, O, F+
Authors: Ou Ming‐Chiu , Chu San‐Yan 
Published: May 2015

AbstractThe bonding in a triatomic molecule XNP and its isomer NPX with X = H+ CH3+, O and F+ was investigated with ab initio molecular orbital calculation using a 6‐31G** basis set at Hartree‐Fock and MP4(sdtq) level. The bonding comparison is based on interaction between NP and X for the two structures. The result that NPX is less stable than XNP is rationalized according to greater promotion energy required for the lone pair of phosphorus in NP to form the P‐X bond than for that of nitrogen to form the N‐X bond. This a energy contribution is counterbalanced by the π energy contribution to a varying extent depending on X.
Determination in Situ of Chemical Solvent Vapors in a Semiconductor Workplace with an Open Path FTIR Spectrometer
Authors: Chang Shih‐Yi , Tso Tai‐Ly , Lo Jiunn‐Gung 
Published: May 2015

AbstractAn FTIR spectrometer having a long absorbing path in an open field mode is applied to measure the air quality of semiconductor facilities, especially for chemical solvent vapors. This spectrometer is demonstrated to be a proper instrument to monitor chemical solvents widely used in the manufacture of integrated circuits. By means of the great sensitivity accruing from the kilometer pathlength, we discovered that many residual chemical solvent vapors are released in these workplaces; the limit of detection can attain the level of parts per billion by volume. Recognized spectra of chemical solvents, such as 2‐ethoxyethyl acetate, 2‐propanol, hexamethyl disilazane, aromatic hydrocarbons, alkyl derivatives of phenol, alkyl benzene sulfonate and dimethyl sulfoxide, are calibrated qualitatively and quantitatively. The related integrated absorption coefficients (or band intensities) are listed in this paper. By examining the measured spectra, we found two chemical solvents (2‐propanoI and hexamethyl disilazane) in the workplace, at concentrations about 20‐500 ppbv in such environments.
Ionization Efficiency of Dicopper Complex in Electrospray Ionization Mass Spectrometry
Authors: Lee Mei‐Kuei , Ling Yong‐Chien , Huang Pei J. , Wang Sung M. 
Published: May 2015

AbstractDicopper complex Cu2(PDTB)(CIO4)4 was analyzed by electrospray technique under varied conditions in order to investigate the effects of important factors on ionization efficiency. The factors taken into account are spray voltage (Vn), temperature of the drying gas, needle layer distance (Dnl), potential difference between the capillary and skimmer (Vcs), potential difference between skimmers 1 and 2 (Vss), and concentration of analyte. The total ion current increases proportionally with Vn varied from 2.0 to 4.0 kV. The ionic stales are not influenced by the variation of Vn and temperature of the drying gas. Variation in nebulization efficiency caused by varied Dnl appears to influence the detected ions in several ways. Structurally characteristic ions are preserved with Vcs smaller than 50 V, dissociate into fragments of smaller molar mass with Vcs 80 V or greater, and disappear with Vcs 200 V or greater. Vss influences the relative intensities of detected ions by an effect of ion focusing. The dependence of the intensity of detected ions on analyte concentration at 10−4 M or greater is ascribed to the principle of equilibrium in solution.
Reaction of (η5‐C5H4R)Fe(CO)2l (R = H, Me) with 1,1′‐Bis(diphenylphosphino)ferrocene (Dppf); Crystal Structure of {[(η5‐C5H5)Fe(CO)(η2‐dppf)]+l−}
Authors: Hsu Ming‐Ann , Yen Wen‐Yann , Chiang Michael Y. 
Published: May 2015

AbstractTreatment of (η5‐RC5H4)Fe(CO)2I (R=H, Me) with 1, 1′‐bis(diphenylphosphino)ferrocene (dppf) in refluxing benzene afforded {[(η5‐RC5H4)Fe(CO)(η2‐dppf)+I} (R = H, 1a; R = Me, 1b), (η5‐RC5H4)‐Fe(CO)1(η2‐dppf) (2a, 2b), and [(η5‐RC5H4)Fe(CO)I]2(μ,η2‐dppf) (3a, 3b). The same reaction catalyzed by [CpFe(CO)2]2 produced only 1a and 1b. Compound 1a crystallizes in space group P1 with a = 11.201(4) Å, b = 13.597(4) Å, c = 14.692(5)Å, α = 78.36(3)° β = 83.58(3)°, γ = 75.00(3)°, V = 2112(1) Å3, Z = 2 and RF = 0.055.
Syntheses and X‐ray Crystal Structures of Dichlorobis(tert‐butylimido) Complexes of Molybdenum(VI); Potential Precursors to Molybdenum Nitride and Molybdenum Carbonitride
Authors: Chiu Hsin‐Tien , Chang Gau‐Banng , Ho Wen‐Yu , Chuang Shiow‐Huey , Lee Gene‐Hsiang , Peng Shie‐Ming 
Published: May 2015

AbstractThe bistertbutylimido complexes [MoCl(μ‐Cl)(NBu1)2(NH2Bu1)]2, 1, and MoCl2(NBu1)2(py)2, 2 (py = pyridine), were prepared by reacting MoCl2(NBu1)2(dme) (dme = dimethoxyethane) with excess Bu1NH2 and pyridine, respectively. Their structures were determined by X‐ray crystallography. 1 has a pseudo edge‐shared bioctahedral geometry with two Cl ligands bridging the Mo centers unequally. Pertinent bond distances and angles for 1, Mo = NBu1beut = 1.737(3) Å, ∠Mo = N‐CMe3 = 154.0(2)°; Mo = NBu1linear = 1.725(3) Å, ∠Mo = N‐CMe3 = 172.4(2)°; Mo‐Bu1NH2 = 2.233(2) Å; Mo‐Clbridging = 2.575(1) and 2.835(1) Å, and Mo‐Clterminal = 2.428(1) Å. Crystal data for 1: triclinic, space group P1, a = 8.897(4) Å, b = 10.518(3) Å, c = 10.663(3) Å, α = 107.68(2)° β = 98.03(3)° γ = 99.26(3)°, V = 919.3(5) Å3, Z = 1, Dc = 1.381 g/mL. 2 is mononuclear with a distorted octahedral geometry with two trans Cl ligands, two cis‐oriented Bu1N = ligands, and two py ligands trans to the imido groups. Pertinent averaged bond distances and angles for 2, Mo = NButbent = 1.736(4) Å, ∠Mo = N‐CMe3 = 163.8(4)°; Mo = NButlinear.= 1.705(5) Å, ∠Mo = N‐CMe3 = 173.4(4)° Mo‐N(py) = 2.44(1), Mo‐Cl = 2.421(3) Å. Crystal data for 2: orthorhombic, space group Pna21 a = 16.860(2) Å, b = 8.920(3) Å, c = 15.120(3) Å, V = 2274.1(9) Å3, Z = 4, Dc = 1.362 g/mL. A potential application of 2 as a single‐source precursor to grow molybdenum nitride and molybdenum carbonitride thin films by low pressure chemical vapor deposition (LPCVD) was explored. Cubic phase thin films (athin film = 4.16–4.20 Å) were grown at temperatures between 450 °C and 650 °C with hydrogen as carrier gas. At 450 °C, thin films of molybdenum nitride were obtained. With temperature of deposition increased from 450 °C to 650 °C, the ratio C/Mo increased from 0.03 to 0.5 whereas me ratio N/Mo decreased from 0.7 to 0.3. Thus, thin films of molybdenum carbonitride were deposited at 650 °C.
Chemistry of Cage‐shaped Hydrocarbons. The Oxidation of Heptacyclo[6.6.0.02,6.03,13.0 4,11.05,9.010,14]tetradecane
Authors: Chow Tahsin J. , Wei Chin‐Chuan , Wu Tung‐Kung 
Published: May 2015

AbstractOxidative ring opening reactions enabled disassembly of the cage structure of the title compound. Stepwise oxidations were achieved through radical intermediates using lead tetracetate and iodine. The regioselectivity of bond fission is rationalized by comparing the relative strains of each bond. Multiple cleavages of C‐C bond were accomplished by photolysis with HgO and iodine under UV. The oxidative effect of Ce(IV) ion on a cage‐shaped diketone is examined. New skeletons of polyquinanes are obtained from these reactions.
Capillary Electrophoresis Separation Techniques and Mechanisms in Dilute Polymer Matrices
Authors: Navin Michael J. , Morris Michael D. 
Published: May 2015

AbstractCapillary electrophoresis in ultradilute derivatized solutions is used to separate nucleic acid fragment mixtures. Pulsed field techniques are used to improve resolution. Protocols in which pulse parameters are varied during the course of the separation are used to increase the range of fragment sizes separated. Fluorescence microscopy is used to study the separation mechanism in ultradilute solution.
Fluorescence Spectra of S2CI Excited with Laser Radiation at 488 nm
Authors: Chiu Chi Lian , Chang Hua 
Published: May 2015

AbstractFluorescence from S2C1 induced by radiation at 488 nm was observed when the parent molecule S2C12 was heated. The dependence of the intensity of fluorescence is third order on laser power. The mechanism of excitation is proposed to be dissociation of hot S2C12 after two‐photon absorption to yield hot S2CI and one‐photon absorption of the latter to reach the fluoresing states. The fluorescence spectrum consists of two systems, called α and β here. The lower state of the a system is the ground state χ and that of the β system is assumed to be the Ã state. The upper states of both systems are unknown but may be related to previously observed slates lying about 460 nm and 330 nm. The vibrational structure of the β system was partially analyzed. The vibrational quantum numbers of the v2 and the v3 modes in the upper state are assessed to be 26 and 0, respectively, from a count of the number of nodes of the curves of the fluorescence intensity distribution. From the abrupt termination of the intensity curve of v2″ progressions, the absolute v2″ quantum numbers were determined. The excitation was in this way assigned to be (p,q + 6,0)′ ← (m,4,n + 3)″, in which p, q, m and n are non‐negative integers.
Effect of the Phase of Titanium Oxide on Metal‐Support Interaction
Authors: Chang Chun‐Show , Jong Sung‐Jeng , Cheng Soofin 
Published: May 2015

AbstractThe metal‐support interaction in the system of platinum supported on titanium oxides of different crystalline structures was investigated. Titanium oxide powders used as supports were prepared by neutralization of TiOCl2‐analogue solution with either NaOH or NH3 base at varied pH. Pt was introduced onto the supports by impregnation. The phenomenon of strong metal‐support interaction (SMSI) was determined by the suppression of chemisorption of H2 over samples reduced at 773 K, in comparison with the behavior of samples reduced at 473 K. The loss of adsorption capacity was proved not due to metal sintering by examining the recovery of adsorption capacity after reduction, reoxidation and reduction cycle, accompanied with examination of the size of Pt particle with an x‐ray diffractiometer and a transmission‐electron microscope. The results showed that SMSI phenomenon was common to Pt supported on titanium oxides of all the varied crystalline structures. However, the chemisorption capacity of Pt reduced at 473 K varied greatly with the sodium content in the supports, which in turns affects the crystalline structure of titanium oxide. These results are attributed mainly to electronic effect endowed by the support.
Kinetics of 2,2′‐Bipyridyl‐Catalyzed Oxidation of Isopropyl Alcohol with Chromic Acid
Authors: Lin Tzucn‐Yeuan , Zeng Han‐Wei , Chuo Chin‐Ming 
Published: May 2015

Abstract2,2′‐Bipyridyl and some substituted compounds catalyze effectively the oxidation of isopropyl alcohol by chromic acid. The reaction is first order in chromium(VI), alcohol and 2,2′‐bipyridyl; it is first order in hydrogen ions at high acidity and slightly alters to second order at low acidity. The proposed mechanism shows that the rate‐limiting step is mainly the decomposition of a termolecular complex to products. However, at low acidity, the formation step of this complex is a little less reversible and hence somewhat rate‐limiting. Electron‐donating substituents at the 4‐position enhance the catalytic activity. Electron‐withdrawing substituents at the 4‐ and 2‐positions diminish the reaction rates by electronic and steric factors.
Intercalation Compounds of Cu2+ and Nl2+ — Exchanged Montmorillonite Clay with 8‐Hydroxyquinoline
Authors: Labhasetwar Nitin K. , Shrivastava O. P. 
Published: May 2015

AbstractMontmorillonite clay mineral shows remarkable ion exchange, intercalation and swelling properties. It can act as a good host for large organic molecules. Intercalated coordination compounds can be prepared in the interlayer spaces of montmorillonite structure. Cu(II)‐ and Ni(II)‐ exchanged montmorillonite sorb 8‐hydroxyquinoline (oxine) to form corresponding coordination compounds of the exchanged metal ions. Such compounds have been characterised by means of elemental analysts, infrared spectroscopy, magnetic susceptibility data and X‐ray diffraction. These compound show good thermal stability.
Chemical Constltuents from the Roots of Zizyphus jujuba Mill. var. spinosa (I)
Authors: Lee Shoei‐Sheng , Wang Jeng‐Shu , Chen Karin Chiung‐Sheue 
Published: May 2015

AbstractThe chemical constituents of the roots of Zizyphus jujuba Mill. var. spinosa were investigated with a combination of Sephadex LH‐20 column, centrifugal partition chromatography and RP‐18 low pressure liquid chromatography. We isolated seven flavonoids‐quercetin (1), (+)‐dihydroquercetin (2), (+)‐dihydrokaempferol (7), quercetin‐3‐0‐β‐glucoside (8), 2‐hydroxynaringenin (11), rutin (12), and quercetin 3‐0‐(2G‐β‐D‐xylopyranosylrutinoside) (13); four catechins‐(‐)‐gallocatechin (3), (‐)‐epigallocatechin (4), (‐)‐catechin (5), and (‐)‐epicatechin (6); and two phenolic carboxylic acids‐p‐hydroxybenzoic acid (9) and protocatechuic acid (10) from the water soluble fraction of the ethanolic extract NMR date of 13 were assigned by 2D NMR techniques.
Structure and Synthesis of Evofolin‐C from Tetradium glabrifolium
Authors: Wu Tian‐Shung , Yeh Jyh‐Her , Wu Pei‐Lin 
Published: May 2015

AbstractA new benzenoid compound evofolin‐C was isolated from the heartwood of Tetradium glabrifolium (Evodia meliaefolia). The structure was elucidated by spectral analysis. The synthesis of evofolin‐C is described.
Femtosecond‐Picosecond Laser Photolysis Studies on Photoinduced Electron Transfer Phenomena in Solutions
Authors: Mataga Noboru 
Published: May 2015

AbstractResults of our femtosecond‐picosecond laser photolysis studies on photoinduced electron transfer phenomena in solutions including exciplex dynamics and its solvent dependences, energy gap dependences of photoinduced charge separation and charge recombination of various geminate ion pairs, mechanisms of chemical reactions via exciplexes and ion pairs, dynamics of photoinduced election transfer in hydrogen bonding complexes, dynamics and mechanisms of photoinduced electron transfer in fixed distance donor acceptor dyads and photosynthetic reaction center models, and mechanisms of electron ejection from solute fluorescent state in polar solutions are summarized and discussed.
Dependence of the Interaction Potentials of Ar‐HF and N2‐HF on HF Bond Length
Authors: Chang Huan‐Cheng , Tao Fu‐Ming , Tsang Susy N. , Klmpcrer William 
Published: May 2015

AbstractWe explore in detail the nature of the intermolecular interactions in two HF containing complexes, ArHF and N2 HF, at vibrationally excited HF stretching states using both high overtone spectroscopic and ab initio computational methods. By using an infrared intracavity laser‐induced fluorescence technique, second overtone spectra of the two HF complexes have been obtained for the HF stretches and their combination modes with low‐frequency van der Waals vibrations. The two complexes show the same trend that both van der Waals bond strength and rotational constant increase smoothly with v of the HF stretch. The investigation of the intermolecular potential above minimum provides a rigorous test of ab initio calculations. In particular for the ab initio calculations using an efficient basis set incorporating bond functions, the technique reproduces reasonably well the anisotropy of the interaction potential of Ar and HF. It is found that the intermolecular potential depends strongly upon the HF bond length only at the linear Ar‐H‐F geometry.
Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions
Authors: Walch Stephen P. 
Published: May 2015

AbstractComputed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NOx and soot formation in hydrocarbon combustion are discussed.
Photon Energy Dependence of the Vibrational Fine Structure in Core Level Photoemission Spectra Near Threshold
Authors: Köppe H. M. , Kilcoyne A. L. D. , Feldhaus J. , Bradshaw A. M. 
Published: May 2015

AbstractThe C 1s and N 1s main lines in the photoelectron spectra of CO, CO2, CH4, C2H2, C2H4, C2H6, N2, and N2O have been measured with high resolution in the threshold region, revealing in each case the extent of the rich vibrational fine structure. Using a simple line shape analysis which allows for the effect of post‐collision interaction, the vibrational energies and approximate lifetimes of the core‐excited ions are determined. The relative intensities of the vibrational lines change dramatically with photon energy due to the influence of shape resonances and double excitations.
The Adsorption and Thermal Decomposition of CH2CO (CD2CO) on Si(111)‐7 × 7
Authors: Bu Y. , Lin M. C. 
Published: May 2015

AbstractThe adsorption and thermal decomposition of ketene on Si(l 11)‐7 × 7 were investigated using various surface analysis techniques. When the surface was exposed to ketene at 120 K, two CO stretching modes at 220 and 273 meV appeared in HREELS, corresponding to two adsorbed ketene states. After the sample was annealed at −250 K, the 273 and the 80 meV peaks vanished, indicating the disappearance of one of the adsorption states by partial desorption of the adsorbate. In a corresponding TPD measurement, a desorption peak for ketene species was noted at 220 K. Annealing the sample at 450 K caused the decomposition of the adsorbate, producing CHx and O adspecies. Further annealing of the surface at higher temperatures resulted in the breaking of the CH bond, the desorption of H and O species and the formation of Si carbide. The desorption of H at 800 K was confirmed by the appearance of the D2 (m/e = 4) TPD peak at that temperature when CD2CO was used instead of CH2CO.
Laser‐Induced Stabilization in Atomic and Molecular Systems
Authors: Chu Shih‐I 
Published: May 2015

AbstractWe present a short account of the recent progress in the study of a novel strong‐field phenomenon recently uncovered: atoms and molecules may be stabilized by intense laser fields. The laser‐induced atomic and molecular stabilization arises from quite different origins. We present a complex‐scaling Fourier‐grid Hamiltonian method for the discretization and solutior of the Schrödinger equation within the non‐Hermitian Floquet Hamiltonian formalism. The method provides a simple, yet accurate and highly efficient, new technique for the determination of the complex quasienergies (ERT −Γ/2) of atoms and molecules. The real parts, ERT provide the a.c. Stark shifts, and the imaginary parts, Γ, give rise to multiphoton ionization rates of atoms or multiphoton dissociation rates of molecules. The method is applied to the studies of (i) stabilization and ionization suppression of negative ions in high‐frequency superintense laser fields; (ii) laser‐induced molecular stabilization and chemical bond hardening in strong laser fields.