咪唑[4, 5-f] 1, 10-邻菲罗啉及其2-取代芳基衍生物的电子结构与光谱性质

分别采用B3LYP/6-31G(d)和CIS/6-31G(d)方法对咪唑[4, 5-f] 1, 10-邻菲罗啉(ip)及其8种2-取代芳基衍生物的基态(S0)和单重激发态(S1)的几何构型进行了全优化, 并采用含时的度泛函理论(TD-DFT)计算了上述化合物的电子吸收和电子发射光谱. 分析了取代基对咪唑[4, 5-f] 1, 10-邻菲罗啉的电子结构、前线分子轨道、电离势Ip、电子亲和势EA及电子光谱的影响. 计算结果表明, 取代基使8种取代衍生物前线分子轨道(LUMO-HOMO)能隙降低,导致其最大吸收和发射波长均发生了红移. 化合物1～8的跃迁类型均为分子内电荷转移（ICT）跃迁,且1～4和5～8的电子转移方向刚好相反. 溶剂对其电子光谱也有影响, 振子强度增大, 最大发射波长红移. 另外, 8种取代衍生物的电离势降低, 电子亲和势增大, 化合物1~4易于空穴的注入, 5~8易于电子的注入.     

咪唑[4, 5-f] 1, 10-邻菲罗啉及其2-取代芳基衍生物的电子结构与光谱性质

分别采用B3LYP/6-31G(d)和CIS/6-31G(d)方法对咪唑[4, 5-f] 1, 10-邻菲罗啉(ip)及其8种2-取代芳基衍生物的基态(S0)和单重激发态(S1)的几何构型进行了全优化, 并采用含时的度泛函理论(TD-DFT)计算了上述化合物的电子吸收和电子发射光谱. 分析了取代基对咪唑[4, 5-f] 1, 10-邻菲罗啉的电子结构、前线分子轨道、电离势Ip、电子亲和势EA及电子光谱的影响. 计算结果表明, 取代基使8种取代衍生物前线分子轨道(LUMO-HOMO)能隙降低,导致其最大吸收和发射波长均发生了红移. 化合物1～8的跃迁类型均为分子内电荷转移（ICT）跃迁,且1～4和5～8的电子转移方向刚好相反. 溶剂对其电子光谱也有影响, 振子强度增大, 最大发射波长红移. 另外, 8种取代衍生物的电离势降低, 电子亲和势增大, 化合物1~4易于空穴的注入, 5~8易于电子的注入.     

Preparation,Chemical Characterization and Electronic Spectra of 6-(2-Pyridylazo)-3-Acetamidophenol and Its Metal Complexes

The stereochemistry of new iron (III), cobalt (II), nickel (II), copper (II), zinc (II) and cadmium (II) complexes of 6-(2-pyridylazo)-3-acetamidophenol (H2L) was studied on the basis of their analytical, spectroscopic, magnetic and conductance data. the dissociation constant of the ligand, as well as the stability constants of its metal complexes had been determined by spectrophotometric method. on the basis of infrared spectra, the coordination behaviour of the ligand to the metal ions was investigated. Magnetic susceptibility and solid reflectance spectra measurements were used to infer the structure. the isolated complexes were found to have the general formulae [M (HL). xH₂O] (A).yH₂O, M = Cu (II), Zn (II), Cd (II) and Fe (HI); HL = 6-(2-pyridylazo)-3-acetamido-phenol; a = acetate in the case of Cu (II) and Zn (II) or chloride in the case of Cd (II) and Fe (Ill), x = 1-3 and y=0-5. for [M (H₂L).xH₂O]Cl₂.yH₂O, M = Ni (II) and Co (II); HL = 6-(2-pyridyl-azo)-3-acetamidophenol, x=3 and y=5-6).     

Analysis of the Tautomeric Properties of Substituted 3-Acryloyltetrahydrofuran-2,4-Dione According to the Data of IR Spectra and Ab Initio Quantum Chemical Calculations

The tautomerism and spectral properties of 3-[3-(4-methoxycarbonylphenyl-acryloyl]tetrahydrofuran-2,4-dione (MCPATD) have been investigated by the methods of nonempirical and semiempirical quantum chemistry (nonempirical calculations by the Möller–Plesset theory of 2nd-order perturbations, calculations by the AM1 and PM3 semiempirical methods), as well as by IR and ¹H NMR spectroscopy. It has been shown that the presence of an additional chain of conjugation in the side chain of MCPATD substantially changes its tautomeric composition and spectral properties as compared to 3-formyl- and 3-acetyltetrahydrofuran-2,4-diones. The frequencies and forms of normal vibrations calculated for each cis-enolic tautomer differ substantially within the region of vibrations of keto groups and double bonds, which makes it possible to identify the tautomers present in the mixture. It is found that in CHCl₃ solutions MCPATD exists as an equilibrium mixture of its exoenolic forms. The possible mechanisms underlying the enol-enolic conversions of MCPATD are discussed.     

The Impact of the Phenyl Spacer on the Electronic Structure and Spectra of Porphyrin Dimers

Quantum-chemical investigation of the electronic structure and properties of the excited states of porphyrin dimers, in which monomeric subunits are linked by the phenyl spacer, is performed by semiempirical methods. The molecular orbitals of the monomeric subunits are shown to interact with each other via molecular orbitals of the phenyl ring. Comparison of the experimental absorption data and quantum-chemical calculations of electronic absorption spectra for different conformations of Zn-tetraphenylporphyrin dimer is performed and the main conformation of the dimer in a solution at 295 K, in which the planes of tetrapyrrole macrocycles are located at an angle of about 60°, is substantiated.