Co-Ligand Involvement in Ground and Excited States of Electron-Rich (Polypyridyl)PtII Complexes

Heterogeneous hydrosilylation reaction catalysed by platinum complexes immobilized on bipyridine-periodic mesoporous organosilicas

A platinum complex immobilized on a bipyridine-periodic mesoporous organosilica (BPy-PMO) effectively catalysed the hydrosilylation reaction and showed good reusability without the loss of the product yield.

First hyperpolarizabilities of Pt(4-ethynylbenzo-15-crown-5)2(bpy) derivatives with the complexation of mono-cations (Li+, Na+, K+) and di-cations (Mg2+, Ca2+): development of a cation detector

The coordination of mono-cations and di-cations onto the crown merits the design of the NLO-based cation detector.

Copper(I) complexes with N-(diisopropoxythiophosphoryl)thiobenzamide PhC(S)NHP(S)(OiPr)2

Reaction of the potassium salt of N-thiophosphorylthiobenzamide PhC(S)NHP(S)(OiPr)(2) (HL) with CuI in aqueous EtOH leads to the tetranuclear [Cu(4)L(4)] and the polynuclear [KCuL(2)](n) complexes, while the same reactions using the lithium or sodium salts of HL exclusively lead to the tetramer [Cu(4)L(4)]. Reaction of KL with the mixture of CuI and 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) leads to the mononuclear complexes [Cu(bpy)L] and [Cu(phen)L]. The same complexes were obtained by the reaction of [Cu(4)L(4)] with bpy or phen.

Cyclometalated iridium and platinum complexes as singlet oxygen photosensitizers: quantum yields, quenching rates and correlation with electronic structures

Photophysical properties are reported for a series of cyclometalated platinum and iridium complexes that can serve as photosensitizers for singlet oxygen. The complexes have the formula (C;N)(2)Ir(O;O) or (C;N)Pt(O;O) where C;N is a monoanionic cyclometalating ligand such as 2-(phenyl)pyridyl and 2-(phenyl)quinolyl, and O;O is the ancillary ligand acetylacetonate (acac) or dipivaloylmethane (dpm). Also examined were a series of (N;N)PtMe(2) complexes where N;N is a diimine such as 2,2'-bipyridyl. In general, the cyclometalated complexes are excellent photosensitizers for the production of singlet oxygen, while the (N;N)PtMe(2) complexes were ineffective at this reaction. Quantum yields of singlet oxygen production range from 0.9-1.0 for the cyclometalated Pt complexes and 0.5-0.9 for Ir complexes. Luminescence quenching and singlet oxygen formation of the Ir complexes occurs from a combination of electron and energy transfer processes, whereas the Pt complexes only react by energy transfer. For Ir complexes with low emission energy, physical deactivation of the triplet excited state becomes competitive with energy transfer to ground state dioxygen. The rates of singlet oxygen quenching for the complexes presented here are in the range 6 x 10(6)-2 x 10(7) M(-1) s(-1) for Pt complexes and 2 x 10(5)-2 x 10(7) M(-1) s(-1) for Ir complexes, respectively. Differences in the efficiency of both forming and quenching singlet oxygen between the Ir and Pt cyclometalates are believed to come about from the more exposed coordination geometry in the latter species.

A new family of luminescent compounds: platinum(ii) imidoylamidinates exhibiting pH-dependent room temperature luminescence

The imidoylamidinate platinum(II) compounds [Pt{NH=C(R)NC(Ph)NPh}2] (R = CH2Ph 2, p-ClC6H43, Ph 4) were prepared by the reaction of the appropriate trans-[PtCl2(RCN)2] with 4 equiv of the amidine PhC(NH)NHPh giving 2-4 and 2 equivs of the salt PhC(=NH)NHPh.HCl. We also synthesized, by the double alkylation of 4 with MeOSO2CF3, complex [Pt{NH=C(Ph)N(Me)C(Ph)=NPh}2][CF3SO3]2 (5) which models the bis-protonated form of 4. The complexes were characterized by 1H, 13C NMR, and IR spectroscopies, FAB-MS and by C, H, N elemental analysis. The X-ray crystallography of 4.2CH2Cl2 enables the confirmation of the square planar coordination geometry of the metal center with almost planar imidoylamidine ligands, while in 5.2CHCl3 the planarity of the metallacycles is lost and and the central N atom is sp3-hybridized. The imidoylamidinate complexes represent a new family of Pt(II)-based luminescent complexes and they are emissive at room temperature both in solution and in the solid state, with an emission quantum yield ranging from 3.7 x 10(-4) to 6.2 x 10(-2) in methanol solution; the emission intensity is pH-dependent, being quenched at low pH. UV-visible and luminescence spectroscopies indicate that the lowest excited state of these compounds is 3MLCT or 3IL with significant MLCT character, with emission lifetimes of a few micros. A blue shift of both the absorption and emission with increasing solvent polarity and with decreasing pi-electron withdrawing properties of the ligand substituent was observed.

Complex Reduction Chemistry of (abpy)PtCl2, abpy = 2,2‘-Azobispyridine: Formation of Cyclic [(μ,η2:η1-abpy)PtCl]22+with a New Coordination Mode for abpy and a Near-Infrared Ligand-to-Ligand Intervalence Charge Transfer Absorption of the One-Electron Reduced State

The structurally characterized (abpy)PtCl2, abpy = 2,2'-azobispyridine, reveals a strong metal/ligand pi interaction as supported by DFT calculations. Unexpectedly, its chemical or electrochemical reduction occurs irreversibly to yield EPR-detectable [(micro,eta2:eta2-abpy)[PtCl2]2]*- and, as the main product of chloride dissociation, the structurally identified and DFT-calculated dinuclear [(micro,eta2:eta1-abpy)PtCl]2(2+) with a novel coordination mode for abpy and isolated as tetrachlorozincate. Stepwise reversible one-electron reduction of that dimer, separated by 0.24 V, exhibits an intense near-infrared band for the monocationic intermediate [(abpy(-I))(abpy)Pt2Cl2]*+ at 1220 nm (epsilon = 3370 M(-1) cm(-1)) which is attributed to a ligand-to-ligand intervalence charge-transfer transition.