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Double-decker platinum complexes with N -heteroaromatic ligands have attracted increasing interest due to their outstanding luminescent properties and rich redox behavior. In this review, the design principles and recent observations on luminescent and redox-active double-decker platinum complexes are discussed. Because these properties are precisely controlled by intra- and intermolecular Pt⋯Pt electronic interactions, double-decker platinum complexes have been also used to obtain phenomena driven by stimulus–responsive color and luminescence change, such as vapochromism, mechanochromism, thermochromism, and electrochromism. This review also summarizes chromic materials based on double-decker platinum complexes influenced by changes in the Pt⋯Pt electronic interactions. [ABSTRACT FROM AUTHOR]

A hybrid vapoluminescent system exhibiting fast and repeatable response was constructed using periodic mesoporous organosilica with bipyridine moieties (BPy-PMO) and a Pt(II) complex bearing a potentially luminescent 2-phenylpyridinato (ppy) ligand. An intense red luminescence appeared when the Pt(II)-complex immobilised BPy-PMO was exposed to methanol vapour and disappeared on exposure to pyridine vapour. The ON-OFF vapochromic behaviour occurred repeatedly in a methanol/pyridine/heating cycle. Interestingly, a rapid response was achieved in the second cycle and cycles thereafter. Scanning and transmission electron microscopies (SEM/TEM), absorption and emission, and nuclear magnetic resonance spectroscopies, mass spectrometry, and powder X-ray diffraction indicated that methanol vapour induced Si-C cleavage and thus liberated [Pt(ppy)(bpy)]Cl (bpy = 2,2′-bipyridine) from the BPy-PMO framework. Furthermore, the self-assembling properties of the Pt(II) complex resulted in the formation of highly luminescent micro/nanocrystals that were homogeneously dispersed on the porous support. The unique vapoluminescence triggered by the unprecedented protodesilylation on exposure to protic solvent vapour at room temperature is attributable to BPy-PMO being a giant ligand and an effective vapour condenser. Consequently, this hybrid system presents a new strategy for developing sensors using bulk powdery materials. [ABSTRACT FROM AUTHOR]

We synthesized a novel Pt(II)--diimine complex with a typical ambidentate thiocyanato ligand, [Pt(thiocyanato)2(H2dcbpy)] (1j H2dcbpy =4,4'-dicarboxy-2)2'-bipyridine), and found that the complex 1 exhibits unique linkage isomerizations with drastic color and luminescence changes driven by exposure to volatile organic chemical (VOC) vapors in the solid state. Reaction between [PtCl2(H2dcbpy)] and KSCN in aqueous solution at 0 °C enabled successful isolation of an isomer with the S-coordinated thiocyanato ligand, [Pt(SCN)2(H2dcbpy)] (1SS·H2O), as a nonluminescent orange solid, Interestingly, 1SS·H2O was isomerized completely to one isomer with the N-coordinated isothiocyanato ligand, [Pt(NCS)2(H2dcbpy)] (1NN·3DMF) by exposure to DMF vapor, and this isomerization was accompanied by significant color and luminescence changes from nonluminescent orange to luminescent red. IR spectroscopy and thermogravimetric analysis revealed that adsorption of the DMF vapor and transformation of the hydrogen-bonded structure both played important roles in this vapor-induced linkage isomerization. Another isomer containing both S- and N-coordinated thiocyanato ligands, [Pt(SCN)(NCS)(H2dcbpy)] (1SN), was obtained as a nonluminescent yellow solid simply by exposure of 1SS·H2O to acetone vapor at room temperature, and about 80% of 1SS&niddot;H2O was found to be converted to ISN. In the solution state, each isomer changed gradually to an isomeric mixture, but pure 1SS was regenerated by UV light irradiation (λirr = 300 nm) of an MeOH solution of the mixture. In the crystal structure of 1SN, the complex molecules were hydrogen-bonded to each other through the carboxyl groups of the H2dcbpy ligand and the N site of the thiocyanato ligand, whereas the 1NN molecules in the 1NN·4DMF crystal were hydrogen-bonded to the solvated DMF molecules. Competition of the hydrogen-bonding abihty among the carboxyl groups of the H2dcbpy ligand, N and S atoms of the thiocyanato ligand, and the vapor molecule was found to be one of the most important factors controlling linkage isomerization behavior in the solid state. This unique linkage isomerization controlled by vapor can provide an outstanding vapochromic system as well as a new molecular sTvitching function driven by vapor molecules. [ABSTRACT FROM AUTHOR]