Coordination-Driven Fluorescent J‑Aggregates in a Perylenetetracarboxylate-Based MOF: Permanent Porosity and Proton Conductivity

Here we report the synthesis and
structural characterizations of
a new 3D functional metal–organic framework {[K8(PTC)2(H2O)1.5]·4H2O}n formed by the self-assembly of KI and chromophoric linker perylenetetracarboxylate (PTC). The
structure determination shows a 3D pillared-layer framework, where
perylene cores are arranged in an unusual end-to-end off-slipped and
zigzag arrangement directed by KI–carboxylate bonding.
Photophysical studies revealed a broad absorption band with λmax of 531 nm and bathochromically shifted red emission centered
at 655 nm. This characteristic emission has been assigned due to J-coupling
of the PTC linkers in the solid state. The framework contains 1D water-filled
channel, and the desolvated framework shows permanent porosity, “as
realized by type-I CO2 adsorption profile at 195 K. Interestingly,
the guest and coordinated water molecules in the framework are connected
via H-bonding and based on these characteristics, the framework was
further exploited for proton conduction. It shows remarkable conductivity
of 1 × 10–3 S cm–1 under
ambient conditions (98% RH) with low activation energy.

本研究报道了一种新型三维功能金属有机框架{[K8(PTC)2(H2O)1.5]·4H2O}n的合成与结构表征，该框架由碘化钾（KI）与发色连接配体苝四羧酸根（perylenetetracarboxylate, PTC）自组装得到。结构解析结果表明，其为三维柱层框架，苝核在碘化钾-羧酸根键合作用的引导下，以罕见的首尾错位堆叠与锯齿形排列方式排布。光物理研究显示，该框架具有宽吸收带，最大吸收波长λmax为531 nm，且存在红移的红色发射峰，峰位位于655 nm处。该特征发射被归因于固态下PTC连接配体之间的J耦合作用。该框架含有一维含水通道，脱溶剂后的框架展现出永久孔隙率，该特性可通过195 K下的I型二氧化碳吸附等温线得以证实。有趣的是，框架中的客体水分子与配位水分子通过氢键相互连接，基于这一特性，该框架被进一步应用于质子传导研究。在环境条件（98%相对湿度，Relative Humidity, RH）下，其展现出1 × 10⁻³ S·cm⁻¹的优异电导率，且活化能较低。