Two series of Bodipy-containing photochromic spirooxazine and spiropyran derivatives have been designed, synthesized and characterized by ¹H NMR, ESI mass spectrometry and elemental analysis. Their electrochemical and photochromic properties were investigated. The photophysical, ultrafast transient absorption, and fluorescence resonance energy transfer (FRET) properties from Bodipy (donor) to the ring-opened merocyanine (acceptor) were also studied. Upon photoexcitation, all the photochromic spirooxazine- and spiropyran-containing compounds exhibited reversible photochromism. Computational studies have been performed to provide further insights into the nature of the electronic transitions for the two classes of compounds. The rate constants and activation parameters for thermal bleaching reactions of compounds SO, SP-alkyne, 1-3, and 8-10 were determined through kinetic studies in acetonitrile. The thermal bleaching reaction rate of the spiropyran-containing compounds is found to be much slower than that of the spirooxazine-containing counterparts.

Lingcan Kong;Hok Lai Wong;Anthony Yiu Yan Tam;Wai Han Lam;Lixin Wu;咏华 任

ACS applied materials & interfaces

2014-2-12

A series of binuclear Re(I) thiolato complexes [{Re(L-L)(CO)₃}₂(μ-SC₆H ₄-X-P)]OTf[L-L = phen, X = CH₃ (1), OCH₃ (2), C(CH₃)₃ (3), Cl (4), F (5); L-L = bpy, X = CH₃ (6); L-L = 5,5′-Me₂-bpy, X = CH₃ (7)] have been synthesized and their photophysical and electrochemical properties studied. The X-ray crystal structure of 6 has also been determined. The complexes have been shown to exhibit long-lived luminescence both in the solid state and in fluid solutions at room temperature. The emission has been assigned as being derived from a ³MLCT origin.

咏华 任;Keith Man Chung Wong;Kung Kai Cheung

Organometallics

1997-4-15

A new class of non-planar and three-dimensional spirobifluorene-modified perylene diimide compounds has been successfully designed and synthesized. The functionalization of the perylene diimide core with different spirobifluorene moieties can alter the molecular geometry as well as extend the spectral coverage into the red region. In addition, these compounds can be utilized as donor materials in combination with fullerene to form bulk heterojunctions, and particularly efficient organic photovoltaic (OPV) devices demonstrating high open-circuit voltages of 0.97 V and a power conversion efficiencies of up to 4% have been prepared. These values are the highest among the cells utilizing p-type perylene diimide as photoactive material in OPV devices. This work opens up a new avenue for the design and synthesis of a new class of p-type perylene diimide compounds that are promising candidates as donor materials in the fabrication of OPV devices.

Chin Yiu Chan;Yi Chun Wong;Hok Lai Wong;Mei Yee Chan;咏华 任

Journal of Materials Chemistry C

2014-9-28

High-quality t-Se nanowires were obtained in high yield via a facile and environmentally benign route in water at room temperature by using ascorbic acid as the reducing agent under the assistance of β-cyclodextrin.

Qing Li;咏华 任

Chemical Communications

2006

A novel class of tetranuclear copper(I) alkynyl complexes with an "open-cube" structure was synthesized. The crystal structure of [Cu₄{P(p-MeC₆H₄)₃} ₄(μ₃-η¹,η¹, η²-C ≡ C-p-MeO-C₆H₄) ₃]PF₆ was determined. These complexes were found to display dual emission behavior. Through systematic comparison studies on the electronic absorption and photoluminescence properties of a series of [Cu ₄(PR₃)₄(μ₃-η¹, η¹,η²-C ≡ CR′)₃] ⁺ complexes, together with density functional theory (DFT) calculations at the PBE1PBE level on the model complex [Cu₄(PH ₃)₄-(μ₃-η¹,η¹, η²-C ≡ C-p-MeOC₆H₄)₃] ⁺, the nature of their emission origins was probed. Their photochemical properties were also investigated by oxidative quenching experiments and transient absorption spectroscopy.

Chui Ling Chan;Kai Leung Cheung;Wai Han Lam;Eddie Chung Chin Cheng;Nianyong Zhu;Sam Wing Kin Choi;咏华 任

Chemistry - An Asian Journal

2006

A new series of platinum(II) complexes with tridentate ligands 2,6-bis(1-alkyl-1,2,3-triazol-4-yl)pyridine and 2,6-bis(1-aryl-1,2,3-triazol-4- yl)pyridine (N7R), [Pt(N7R)Cl]X (1-7) and [Pt(N7R)(Cï£CR′)]X (8-17; R=n-C₄H₉, n-C₈H₁₇, n-C ₁₂H₂₅, n-C₁₄H₂₉, n-C ₁₈H₃₇, C₆H₅, and CH ₂-C₆H₅; R′=C₆H₅, C₆H₄-CH₃-p_, C₆H ₄-CF₃-p, C₆H₄-N(CH₃) ₂-p, and cholesteryl 2-propyn-1-yl carbonate; X=OTf^-, PF₆^-, and Cl^-), has been synthesized and characterized. Their electrochemical and photophysical properties have also been studied. Two amphiphilic platinum(II)-2,6-bis(1-dodecyl-1,2,3-triazol-4-yl) pyridine complexes (3-Cl and 8) were found to form stable and reproducible Langmuir-Blodgett (LB) films at the air/water interface. These LB films were characterized by the study of their surface-pressure-molecular-area (π-A) isotherms, XRD, and IR and polarized-IR spectroscopy.

Yongguang Li;Le Zhao;Anthony Yiu Yan Tam;Keith Man Chung Wong;Lixin Wu;咏华 任

Chemistry - A European Journal

2013-10-18

Gold(III) alkynyl complexes with dianionic tridentate pincer ligands have received growing attention recently because of their rich luminescence behavior and their potential applications in areas such as optoelectronics and sensors. In this study, density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed to investigate the radiative and nonradiative processes for the gold(III) alkynyl complexes with different dianionic tridentate ligands, [Au(C^N^C)(≡CC₆H₅)] (1; C^N^C = 2,6-diphenylpyridine), [Au(C(Np)^N^C(Np))(≡CC₆H₅)] [2; C(Np)^N^C(Np) = 2,6-di(2-naphthyl)pyridine], [Au(N^N^N)(≡CC₆H₅)] [3; N^N^N = 2,6-bis(benzimidazol-2′-yl)pyridine], and [Au(C^C^N)(≡CC₆H₅)] [4; C^C^N = 3-(2-pyridyl)biphenyl]. It has been found that the electronic properties of the tridentate ligand could have a significant impact on the radiative and nonradiative processes. This study provides an in-depth understanding on the effect of the dianionic pincer ligands on the different photophysical behaviors among the gold(III) alkynyl complexes and crucial information for the future design of gold(III) complexes in various applications.

Elizabeth Suk Hang Lam;Wai Han Lam;咏华 任

Inorganic Chemistry

2015-4-6

咏华 任;Phyllis Kok Yan Yeung;Kung Kai Cheung

Angewandte Chemie - International Edition

1996

A series of dithienophosphole compounds has been successfully synthesized and characterized by photophysical, electrochemical, and thermal studies. Possessing the electron-deficient dithienophosphole oxide moiety, these compounds are found to display strong intramolecular charge transfer character and exhibit high photoluminescence quantum yields of up to 0.68. Taking advantage of the properties, these phosphole-based compounds have been applied as active materials in the fabrication of organic photovoltaics (OPVs), organic light-emitting devices (OLEDs) and organic resistive memory devices. Satisfactory performances with power conversion efficiencies of up to 4.23% for OPV devices, external quantum efficiencies of up to 3.0% for OLEDs, and binary resistive memories with retention time of over 10000 s and distinctive OFF/ON current ratio of 1:10⁷ have been realized based on these dithienophosphole compounds. These findings revealed the multifunctional behavior of these dithienophosphole compounds and represent for the first time the use of phosphole-based small molecules as donor materials for the vacuum-deposited OPV devices.

Yat Hin Cheng;Hok Lai Wong;Eugene Yau Hin Hong;Shiu Lun Lai;Mei Yee Chan;咏华 任

ACS Applied Energy Materials

2020-3-23

The exploration of phosphorescent materials based on transition metal-ligand chromophoric complexes represents an important area of research in molecular materials. The knowledge and fundamental understanding of their photophysical properties offer a possible fine-tuning of their electronic absorption and luminescence properties. The strong propensity of d⁸ transition metal compounds to form non-covalent metal··· metal interactions facilitates supramolecular assembly and the formation of supramolecular nanostructures with interesting photophysical properties. The introduction of supramolecular assembly with hierarchical complexity involving non-covalent interactions could lead to research dimensions of unlimited possibilities and opportunities. This article briefly summarizes the latest progress on the use of d⁸ metal-ligand chromophores as chemosensors, as exemplified by alkynylplatinum(II) complexes with emphasis on supramolecular assembly involving non-covalent interactions, and the recent advances in the utilization of d⁸ metal-ligand phosphors, as exemplified by alkynylgold(III) system, for the exploration and development of phosphorescent OLEDs.

Keith Man Chung Wong;Maggie Mei Yee Chan;咏华 任

Advanced Materials

2014-8-20