Synthesis and photophysical and electrochemical properties of new cyclometalated platinum complex containing oxadiazole ligand

A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated. A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about 、5.69 and 、3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.

Cyclometalated Ruthenium Complexes of 1,2,3-Triazole-containing Ligands： Synthesis, Structural Studies, and Electronic Properties

Six bis-tridentate and two tris-bidentate cyclometalated ruthenium complexes with a 1,2,3-triazole-containing ligand have been prepared and characterized. Single-crystal X-ray analyses of complexes [（MeOptpy）Ru（Budtab）]-（PF6） and [（Mebip）Ru（Budtab）]（PF6） are presented, where MeOptpy is 4′-p-methoxyphenyl-2,2′：6′,2＂-terpyridine, Budtab is the 2-deprotonated form of 1,3-di（N-n-butyl-l,2,3-triazol-4-yl）benzene, and Mebip is bis（N-methyl-ben-zimidazolyl）pyridine. The electronic properties of these complexes are probed by spectroscopic and electrochemical analyses. Time-dependent density functional theory calculations have been performed to assist the assignment of the absorption spectra.

Study on Cyclometalated Palladium-azo Complexes as Colorimetric Probes for Hazardous Gas in Water

A synthesized cyclometalated palladium-azo complex was explored as a multifunctional probe for visual detection of SO2, H2S and NH3 in water. In acidic aqueous environment, the sensing solution underwent a sharp color change from poor violet to deep blue when titrated with Na2SO3 standard solution. But the color changed from poor violet to bright yellow when titrated with Na2S standard solution. In basic environment, the sensing solution rapidly changed to magenta when titrated by NH4Cl-NH3 standard buffer solution at high concentration. However, the color of sensing solution changed to blue when titrated by NH4Cl-NH3 standard buffer solution at low concentration although the pH was kept constant during the titration. Different species of these hazardous gases at environmentally relevant concentration levels were differentiated by independent optical signal outputs, and the interference from other inorganic ions commonly existing in water was very small.

Advances on supramolecular assembly of cyclometalated platinum(Ⅱ) complexes

Organoplatinum（Ⅱ） compounds have received enormous attention over the past decades due to their square-planar geometry as well as intriguing photo-physical properties.Self-assembly has emerged as an excellent approach to create well-ordered supramolecular architectures with tunable properties,which underpin the role of solvent-directed approach for the design of functional materials.In this minireview,the recent advances on supramolecular self-assembly of cyclometalated platinum（Ⅱ） complexes have been discussed.During the self-assembly process,non-covalent Pt-Pt and π-π interactions play crucial roles in controlling the structures and functions of the resulting assemblies.

Tuning the Excited-state Properties of Cyclometalated Platinum(II) Complexes of 6-Phenyl-2,2′-bipyridine by Ancillary Acetylide Ligand

A series of luminescent cyclometalated platinum(II) complexes, (C^N^N)Pt(C≡CR) [HC^N^N=4 (4 tolyl) 6 phenyl 2,2′ bipyridine; R=4 chlorophenyl (1), phenyl (2) and 4 tolyl (3)], were synthesized, and their spectroscopic properties have been examined. These complexes are brightly emissive both in fluid solution and in the solid state, attributed to triplet metal to ligand charge transfer ( 3MLCT) state. The excited state energy can be tuned by ancillary acetylide ligands. The emission lifetimes in dichloro^methane solution at room temperature were up to 1 64 μs and the emission quantum yields were in the range of 0 03-0 15.

Molecular design and theoretical investigation into one-and two-photon absorption properties of two series of cyclometalated platinum(Ⅱ) complexes

We have theoretically investigated two series of cyclometalated Pt（II） complexes, a series [Pt （C, N, N） Cl] and b series [Pt （C, N, Npyrazolyl） Cl]. The geometrical and electronic structures are calculated at the ECP60MWB//6-31G＊（H, C, Cl, N, S） basis set level using DFT method; one-photon absorption （OPA） properties are calculated by using both TDDFT and ZINDO methods and two-photon absorption （TPA） properties are obtained with the ZINDO/SOS method. The resonance integrals parameters （βsp and βd） for Pt are adjusted to -1 and -28.5 eV, respectively, to make max OPA wavelength calculated by ZINDO closest to the experimental data and TDDFT results. The calculated results indicate the molecule 2b （[Pt （Cnaphthyl, N, Npyrazolyl） Cl]） has the biggest potential as outstanding TPA materials because （i） the TPA properties of b series are more outstanding in IR wavelength range, the molecules in b series have good transparencies and possess 1-pyrazolyl-NH that is also available for another metal coordination （e.g., dimerization） and chemical interactions; （ii） when C is CnaphthyI in the C, N, N ligand of cyclometalated Pt（II） complexes, the molecules have the best conjugation effect and the best TPA properties.

New cyclometalated transition-metal based photosensitizers for singlet oxygen generation and photodynamic therapy

The aim of this review article is to introduce recent studies on an emergent class of singlet oxygen photosensitizers of potential applications to the photodynamic therapy,with a primary focus on the cyclometalated transition-metal complexes.Singlet oxygen photosensitization performances of various cyclometalated Ir and Pt scaffolds are reviewed,and the general photophysical properties of relevant systems and the mechanisms of singlet oxygen production via photo-sensitization are also briefly discussed.Thus far,investigations of singlet oxygen sensitization by such Ir and Pt complexes are mainly carried out in organic solvents and under non-physiological conditions,while some research efforts have been made at examining the feasibility of applying pertinent cyclometalated complexes to photodynamic therapy.

Structural, Electronic and Optical Properties of Multifunctional Iridium（III） and Platinum（II） Metallophosphors for Organic Light-Emitting Diodes

An elaborated theoretical investigation on the optical and electronic properties of three fluorene-based plati- num（II） and iridium（III） cyclometalated complexes Pt-a, Ir-a and lr-b is reported. The geometric and electronic structures of the complexes in the ground state are studied with density functional theory and Hartree Fock ap- proaches, while the lowest triplet excited states are optimized by singles configuration interaction （CIS） methods. At the time-dependent density functional theory （TD-DFT） level, molecular absorption and emission properties were calculated on the basis of optimized ground- and excited-state geometries, respectively. The computational results show that the appearance of triphenylamino （TPA） moiety at the 9-position of fluorene ring favors the hole-creation and leads to red-shifts of absorption and emission spectra. Moreover, Pt-a and Ir-b are nice hole-transporting materials whereas Ir-a has good charge-transfer balance, which render them useful for the realiza- tion of efficient OLEDs （Organic Light-Emitting Diodes）.

pH-responsive aldehyde-bearing cyclometalated iridium(Ⅲ) complex for tracking intracellular pH fluctuations under external stimulation

Intracellular p H undertakes critical functions in various biological and pathological processes. It is important to monitor intracellular p H fluctuations for understanding physiological and pathological processes.Here, one aldehyde-bearing cyclometalated iridium(Ⅲ) complex([(4-pba)_(2)Ir(dcphen)]PF_(6), 4-pba = 4-(2-pyridyl) benzaldehyde, dcphen = 4,7-dichloro-1,10-phenanthroline, probe 1) was synthesized and used to track intracellular p H fluctuations. Probe 1 displayed p H-dependent luminescence property in p H range of 1.81–6.81 with an evaluated p Kavalue of 4.30 in BR buffer-DMSO(v:v = 99:1). An intramolecular hydrogen bonds assisted p H-responsive mechanism was proposed for the p H-responsive behavior of probe1. Probe 1 was successfully applied for imaging and tracking p H fluctuations in He La cells under external stimulation with fast response time, good photostability as well as low cytotoxicity and high cell permeability. This work demonstrates that aldehyde-bearing cyclometalated iridium(Ⅲ) complex can be used as alternative p H-responsive probe for real-time tracking intracellular p H fluctuations, which provides a strategy for the design of p H-responsive probe in versatile applications.