Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore-560 064, India.
Chemistry. 2012 Jan 2;18(1):237-44. doi: 10.1002/chem.201101183. Epub 2011 Dec 5.
A 3D porous Zn(II) metal-organic framework {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)(H(2)O)]·4H(2)O} (1; H(2)dht=dihydroxyterphthalate, azpy=4,4'-azobipyridine) has been synthesised by employing 2,5-dihydroxyterephthalic acid (H(4)dht), a multidentate ligand and 4,4'-azobipyridine by solvent-diffusion techniques at room temperature. The as-synthesised framework furnishes two different types of channels: one calyx-shaped along the [001] direction and another rectangle-shaped along the [101] direction occupied by guest water molecules. The dehydrated framework, {[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)]} (1') provides 52.7% void volume to the total unit-cell volume. The pore surfaces of 1' are decorated with unsaturated Zn(II) sites and pendant hydroxyl groups of H(2)dht linker, thereby resulting in a highly polar pore surface. The dehydrated framework 1' shows highly selective adsorption of CO(2) over other gases, such as N(2), H(2), O(2) and Ar, at 195 K. Photoluminescence studies revealed that compound 1 exhibits green emission (λ(max)≈530 nm) on the basis of the excited-state intramolecular proton-transfer (ESIPT) process of the H(2)dht linker; no emission was observed in dehydrated solid 1'. Such guest-induced on/off emission has been correlated to the structural transformation and concomitant breaking and reforming of the OH···OCO hydrogen-bonding interaction in the H(2)dht linker in 1'/1.
一种 3D 多孔 Zn(II) 金属有机骨架{[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)(H(2)O)]·4H(2)O}（1；H(2)dht=二羟对苯二甲酸，azpy=4,4'-联吡啶）通过使用二羟对苯二甲酸（H(4)dht），一种多齿配体和 4,4'-联吡啶，在室温下通过溶剂扩散技术合成。合成的骨架提供了两种不同类型的通道：一种沿[001]方向呈冠形，另一种沿[101]方向呈矩形，由客体水分子占据。脱水骨架{[Zn(2)(H(2)dht)(dht)(0.5)(azpy)(0.5)]}（1'）为总单元体积提供了 52.7%的空隙体积。1'的孔表面由不饱和 Zn(II)位和 H(2)dht 配体的悬垂羟基基团装饰，从而导致高度极性的孔表面。脱水骨架 1'在 195 K 时表现出对 CO(2)的高选择性吸附，超过其他气体，如 N(2)、H(2)、O(2)和 Ar。荧光研究表明，化合物 1 基于 H(2)dht 配体的激发态分子内质子转移（ESIPT）过程表现出绿色发射（λ(max)≈530nm）；在脱水固体 1'中没有观察到发射。这种客体诱导的开/关发射与结构转化以及 H(2)dht 配体中 OH···OCO 氢键的断裂和形成相关联在 1'/1 中。
