Dongfang Qiu

Cyclometalated Platinum(II) Terpyridylacetylide with a Bis(arylamine) Donor as a Proton-Triggered Luminescence Chemosensor for Zn2+

A cyclometalated Pt(II) acetylide derivative bearing a bis(arylamine) donor (D) and a terpyridine (TPY) receptor (A) was successfully synthesized and characterized. This three-component D-π-A system displays an intense low-energy absorption band at λmax = 470 nm, resulting from overlapping the dπ(Pt) → π*(C^N^N) metal-to-ligand charge transfer and π(C≡C-Ar) → π*(C^N^N) ligand-to-ligand charge transfer transitions with the π(bis(arylamine)) → π*(C^N^N) intraligand charge transfer transition. Upon protonation of the bis(arylamine) donor, a strong emission from the phosphorescence Pt(II) complex unit is recovered at λmax = 580 nm. With introduction of the TPY receptor, this complex possesses quite high affinity for Zn(2+) (Ka = 6.86 × 10(9) mol(-2)·dm(6)) to form the heterotrinuclear Pt-Zn-Pt complex in CH2Cl2 solution. Though this coordination effect is seriously inhibited by protons in acidic medium, the 2.4-fold luminescence intensity enhancement is obtained yet, strongly suggesting the presence of the intramolecular energy transfer process from the Zn(II)-TPY complex core to the phosphorescence Pt(II) complex units at two ends. The H(+)-triggered and Zn(2+)-enhanced luminescence can be reversibly switched on and off upon successive additions of H(+) and OH(-). Furthermore, this complex displays an unexpected Zn(2+)-selective luminescence enhancement effect in acidic solution.

Electrochromic and proton-induced phosphorescence properties of Pt(II) chlorides with arylamine functionalized cyclometalating ligands

Two cyclometalated Pt(II) complexes, [(L1)PtCl] and [(L2)PtCl] (where HL1 = 4-[p-(N-octyl-N-phenyl)amino]-phenyl-6-phenyl-2,2′-bipyridine and HL2 = 4-{p-[p-(N,N′-dioctyl-N′-phenyl)phenyldiamino]}-phenyl-6-phenyl-2,2′-bipyridine), have been synthesized and characterized by 1H NMR, mass spectrometry (MS) and elemental analysis. The structure of complex [(L1)PtCl] has been revealed by X-ray crystallography. Both of the complexes possess the intense and red-shifted metal-to-ligand charge transfer (1MLCT) (dπ(Pt) → π*(L)) transitions (e ∼ 104 dm3 mol−1 cm−1). Complex [(L1)PtCl] displays strong phosphorescence (λmax = 597 nm) in CH2Cl2 solution at room temperature and efficient electropolymerization behavior to form an electrochromic film with times of 5.8 s for the coloration step and 5.2 s for the bleaching step, an optical contrast of 70.5%, a black coloration efficiency of 441.4 C−1 cm2 and a bleaching efficiency of 489.1 C−1 cm2. Complex [(L2)PtCl] shows sensitive pH dependent luminescent properties, which are attributed to the inhibition of the intramolecular charge transfer (ICT) process through the protonation of the aniline dimer unit in the cyclometalating ligand.

A novel open-framework copper borovanadate with enhanced catalytic performance for oxidation of benzylic C-H bond

A novel open-framework copper borovanadate, with a 6-connected topological net and 1D 8-membered ring channels, has been obtained for the first time. The compound not only exhibits a unique -B3 O7 (OH)-Cu-B(OH)3 linkage and features the largest ratio between TM2+ (Cu2+ ) and the borovanadate anion, but also possesses enhanced catalytic performance, high recyclability, and stability during the oxidation of benzylic C-H bonds.

Synthesis, crystal structure, photophysical property and metal ion-binding behavior of a cyclometalated platinum(II) terpyridylacetylide with efficient π-conjugation degree

A cyclometalated Pt(II) acetylide derivative bearing a carbazole donor and a terpyridine (TPY) receptor has been successfully synthesized and characterized. X-ray crystallography shows its monoclinic crystal system with the P2(1)/c space group and the three-component co-planarity molecular structure. This efficient π-conjugation system displays an intense low-energy absorption band (e = 1.51 × 104 dm3 mol−1 cm−1) at λmax = 442 nm and a strong phosphorescence emission (Φ = 0.045) at λmax = 596 nm in an air-saturated CH2Cl2 solution at room temperature, resulting from the dπ(Pt) → π*(C^N^N) metal-to-ligand charge transfer (MLCT) mixing with the π(CC–Ar) → π*(C^N^N) ligand-to-ligand charge transfer (LLCT) transition. With the introduction of the TPY receptor, this complex possesses ca. 1.6-fold luminescence-enhancing response for Zn2+ and Cd2+ but dramatic luminescence quenching response toward other common transition metal cations. Consecutive titrations exhibit that the added metal ions bond to its free TPY receptor with 1 : 2 stoichiometry to form the heterotrinuclear (Pt–M–Pt) complex. The Fe2+-quenched and Zn2+-enhanced luminescence behaviors with the maximum PET efficiency of 92.4% and 62.7%, respectively, strongly suggest the presence of the intra-molecular energy transfer between the [M(TPY)2]2+ core and the terminal phosphorescent Pt(II) complex units.

Synthesis, crystal structure and electrochemical property of 2D lamellar supermolecular complex [Cu(C6H4NO2)2 · H2O]

A 2D lamellar supermolecular complex [Cu(C6H4NO2)2 · H2O] was synthesized and characterized by elementary analysis, infrared spectrum, ultraviolet spectrum, thermogravimetry analysis and crystal X-ray diffraction analysis. The complex belongs to the orthorhombic system, Pbca space group, with a = 1.2797(8), b = 1.2944(8), c = 1.4962(9) nm, Z = 8, V = 2.478(3) nm3, Dc = 1.746 g cm−3, μ = 1.784 mm−1, F(000) = 1320, R1 = 0.0267, wR2 = 0.0762, GOOF = 1.015, which consists of a Cu(II) ion, two 2-Picolinic acid and a coordinated water molecule. The 5-coordinated geometry of the Cu cation is a distorted tetragonal-pyramidal configuration. The 1D chain structure is formed through hydrogen bonds O(w)-H…O between single cells, and the 2D lamellar supermolecular system is formed through the non-classical hydrogen bonds C-H…O between various chains. The complex displays a distinct absorption band (λmax = 648 nm) in aqueous solution. The electrochemical behavior shows a quasi-reversible course. (CCDC: 750880)