Structure and Photophysical Properties of a Chiral 4-Fold Interpenetrated Zn(Ⅱ) Coordination Polymer Tuned by 4,4'-(Hexafluoroisopropylidene)bis(benzoic acid)and 1,3-Di(pyridineyl)benzene

A new three-dimensional（3D） chiral metal-organic coordination polymer, [Zn（dpb）（hfipbb）]n, was obtained under hydrothermal conditions by 1,3-di（pyridineyl）benzene（dpb） and 4,4-（Hexafluoroisopropylidene）bis（benzoic acid）（H2hfipbb）. The as-prepared sample was characterized by single-crystal X-ray diffraction, PXRD, elemental analysis, IR spectroscopy and TGA analysis. The title coordination polymer crystallizes in orthorhombic, space group P21212, with a=21.923（4）, b=23.594（4）, c=7.3042（13） , V=3778.1（12） 3, Dc=1.209 g/cm3, Mr=687.90, F（000）=1328, μ=0.713 mm（-1） and Z=4. The compound contains two types of helical chains [Zn（hfipbb）]n and [Zn（dpb）]n which are linked with each other to generate a 3D framework by sharing the same Zn（Ⅱ） cations. It displays a 4-fold interpenetrated 3D framework. In addition, the luminescence, fluorescence lifetime and the second harmonic generation（SHG） efficiency properties in the solid state have been studied.

Research Advances in Helicene Structure-Based Chiral Luminescent Materials and Their Circularly Polarized Electroluminescence

Benefited from direct generation of circularly polarized(CP) emission with tunable colors, high efficiencies and facile device architectures, CP organic light-emitting diodes(CP-OLEDs) have attracted great attention and are expected to meet industrial applications. Particularly, CP electroluminescence(CPEL) originated from CP-OLEDs has wide potential applications in 3D displays, optical information storage, quantum communication, and biological sensors. The diverse design strategies of chiral luminescent materials for CP-OLEDs, including small organic emitters, lanthanide and transition-metal complexes and conjugated polymers, have been extensively explored. Helicene with twisted extended π-conjugated molecular structure could exhibit special helical chirality and excellent circularly polarized luminescence properties, which has been employed as the ingenious chirality core for constructing efficient chiral luminescent materials. In addition, significant improvements have been made in terms of CP photoluminescence research, however, the development of CPEL with more application prospects in optoelectronic technology still lags behind. In this review, we systematically summarize the recent advances in chiral luminescent materials based on helicene structure and their CPEL properties, including helicene-based chiral fluorescence molecules, transition metal complexes and thermally activated delayed fluorescence molecules, and discuss current challenges and future perspectives for this hot research field. We believe this progress report will provide a promising perspective of OLEDs based on helicene emitters with CPEL properties for extensive researchers, including chemical, physical and material scientists in different disciplinary fields and attract them to this rapidly developing field.