M. A. Ivanov

Spectral and luminescent specific features of phenylpyridine ethylenediamine complexes of Pt(II), Pd(II), and Au(III)

The orbital nature and basic photophysical parameters of phenylpyridine ethylenediamine complexes of Pt(II), Pd(II), and Au(III) are found from the comparative analysis of absorption and luminescence spectra and the luminescence decay kinetics. The orbital nature and properties of the lowest excited states responsible for luminescence are shown to depend on the type of metal and the energy of singlet-triplet splitting.

Effect of heterocyclic diimine ligands with donor and acceptor substituents on the spectroscopic and electrochemical properties of Au(III) complexes

The composition, structure, and properties of a series of Au(III) complexes with heterocyclic diimine ligands [Au(N^N)Cl2]+, where (N^N) = 2,2′-bipyridine (Bipy), 4,4′-dimethyl-2,2′-bipyridine (DmBipy), 2,2′-biquinoline (Bqx), 1,10-phenanthroline (Phen), 2,9-dimethyl-1,10-phenanthroline (DmPhen), and 4,7-diphenyl-1,10-phenanthroline (DphPhen), were characterized by 1H NMR, electronic absorption, and emission spectroscopy and also by cyclic voltammetry. The influence of donor and acceptor substituents on the spectroscopic and electrochemical properties of the Au(III) complexes was revealed.

Spectroscopic and electrochemical properties of mixed-ligand cycloplatinated complexes based on 2-(2-thienyl)pyridine and 2-phenylpyridine with 1,10-phenantroline and its 1,4-diazine derivatives

A comparative study of dipyrido-and dibenzo-substituted 1,4-diazines {dipyrido[f,h]quinoxaline (dpq), dipyrido[a,c]phenazine (dppz), 6,7-dicyanodipyrido[f,h]quinoxaline (dicnq), dibenzo[f,h]quinoxaline, dibenzo[a,c]phenazine, 6,7-dicyanodibenzo[f,h]-quinoxaline}, o-phenantroline (phen), and also of the complexes [Pt(N∧C)(N∧N)]+[(N∧C)− are deproronated forms of 2-phenylpyridine and 2-(2-thienyl)pyridine; (N∧N) is ethylenediamine, phen, dpq, dppz, dicnq] was carried out by the methods of 1H NMR, electronic absorption, and emission spectroscopy and by cyclic voltammetry. It was found that in frozen solutions of [Pt(N∧C)·(N∧N)]+ complexes the photoexcitation energy decay from two lowest in energy electronic excited states has isolated character and is localized on {Pt(N∧C)} and {Pt(N∧N)} metal-complex fragments: (d-πN∧C*) and (d-πphen*) [(N∧N) = phen, dpq, dicnq)] or (d-πN∧C*) and (π-πdiaz*) [(N∧N) = dppz]. Thermal quenching of the luminescence from the (d-πphen*) and (π-πdiaz*) states gives rise to luminescence of the complexes in liquid solutions at 293 K only from the (d-πN∧C*) state.

Spectral properties of 2-phenylpyridinate complexes of Au(III) with diimine ligands

The synthesis, identification, and optical spectra of 2-phenylpyridinate complexes of Au(III) with diimine ligands (2,2′-bipyridyl and 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline) are described. A difference in the nature of the energetically lowest electronically excited states responsible for the luminescence is established.

Preparation and spectroscopic and electrochemical properties of complexes of dibenzo- and dipyrido-substituted 1,4-diazines

The spectroscopic and electrochemical properties of palladium ethylenediamine complexes [Pd(N^N)En]Cl2 with 1,4-diazine derivatives of o-phenanthroline [(N^N) = dipyrido[a,c]phenazine (dppz), dipyrido[f,h]quinoxaline (dpq)] were studied in comparison with those of the free diimine (N^N) ligands, dibenzo-substituted 1,4-diazines [dibenzo[f,h]quinoxaline (dbq), dibenzo[a,c]phenazine (dbpz)], and cyclometallated dichloride [Pd(C^N)(μ-Cl)]2 and ethylenediamine [Pd(C^N)En]Cl complexes derived from dibenzo-substituted 1,4-diazines.

Spectroscopic and electrochemical properties of dichlorodiimine complexes of Au(III) and Pt(II) with 1,4-diazine derivatives of o-phenanthroline

A series of dichlorodiimine complexes [M(N N)Cl2]z of Au(III) and Pt(II) with 1,4-derivatives of o-phenanthroline [(N N) = o-phenanthroline (phen), dipyrido[f,h]quinoxaline (dpq), dipyrido[a,c]phenazine (dppz), 6,7-dicyanodipyrido[f,h]quinoxaline (dicnq)] were prepared and characterized by 1H NMR, electronic absorption, and emission spectroscopy and by cyclic voltammetry. In all the complexes, the 3(π-π*)-type transition is the spin-forbidden transition of the lowest energy, responsible for the luminescence. The longest wave bands in the absorption spectra of the Au(III) and Pd(II) complexes were assigned in accordance with the results of the electrochemical studies to the 1(d*)-and 1(d*)-type transitions, respectively.

Spectroscopic and electrochemical properties of mixed-ligand cyclopalladinized complexes of deprotonated forms of 2-(2-thienyl)pyridine and 2-phenylpyridine with 1,10-phenantroline and its 1,4-diazine derivatives

A comparative study of [Pd(N⋀C)(N⋀N)]+ complexes {(N⋀C)− are deprotonated forms of 2-phenylpyridine and 2-(2-thienyl)pyridine and (N^N) is 1,10-phenantroline, dipyrido[f,h]quinoxaline, dipyrido[a,c]phenazine or 6,7-dicyanodibenzo[f,h]quinoxaline} was carried out by the methods of 1H NMR, electronic absorption and emission spectroscopy, and cyclic voltammetry. Optical and electrochemical properties of dipyrido-substituted 1,4-diazines are conditioned by the electron transfer involving π* orbitals localized on weakly interacting phenantroline (π*phen) and diazne (π*diaz) components.

Spectral and luminescent properties of mixed-ligand complexes of palladium(II) and 7,8-benzoquinoline

Spectral and luminescent properties of mixed-ligand palladium(II) complexes—[PdBhq(μ-Cl)]2, [PdBhqEn]ClO4, and [PdBhqBpy]ClO4, where Bhq stands for the 7,8-benzoquinoline ion—were studied. The absorption spectra of these complexes in the 25000–40000-cm− range were found to have a number of spin-allowed transitions of the 1(π-π*) type involving orbitals of the 7,8-benzoquinoline ligand. The luminescent characteristics of these compounds in a glass-forming matrix at 77 K are primarily determined by the participation of the 3(π-π*) states of the 7,8-benzoquinoline ligand.

Effect of the nature of heterocyclic ligands on spectral and luminescent properties of Pt(II) and Pd(II) complexes

The spectral and luminescent properties of Pt(II) and Pd(II) complexes with heterocyclic imine ligands—1-phenylpyrazolate, 2-phenylpyridinate, and 2,2′-bipyridyl—are studied. It is found that the field strength of these ligands satisfies the following relation: Ppy−>Bipy≈Ppz−.

Synthesis and spectroscopic and electrochemical properties of binuclear complexes of Au(III) bridged by 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline

A method of synthesis of new diimine complexes of Au(III) with a four-dentate bridging ligand 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline (Ddpq), [Au2(μ-Ddpq)Cl4]Cl2 and [(AuN^N)2(μ-Ddpq)](NO3)6, where N^N is ethylenediamine, 2,2′-bipyridyl, or 1,10-phenanthroline, is described and the composition, structure, and properties of these complexes are studied. The coordination-induced chemical shifts in the 1H NMR spectra are determined, as well as the spectral-luminescent and electrochemical parameters of the complexes. The nature of the energetically lowest spin-allowed 1(π-d*)-and spin-forbidden 3(π-π*) states is established.