A Unique Optical and Electrical Multifunctional Metal−Organic Framework Based on Polynuclear Rod-Shaped Secondary Building Units Constructed from a “Three Birds with One Stone” in Situ Reaction Process

A unique three-dimensional metal−organic framework (MOF) [Cd₄(1,10′-phen)(fum)(S-mal)(R-mal)(H₂O)] (1) (1,10′-phen =1,10-phenanthroline, fum = fumarate dianion, mal = malate dianion) has been synthesized and characterized by single-crystal X-ray analysis. Under hydrothermal conditions, after a “three birds with one stone” in situ reaction process, maleic acid turns into fumarate dianion, isomeric R-malate dianion and S-malate dianion, which further connect with Cd atoms and form an octanuclear Cd cluster. The octanuclear Cd cluster links with neighboring clusters and constructs a rod-shaped secondary building unit (SBU). Neighboring rod-shaped SBUs are further connected by fumarate dianions and thus forms a three-dimensional network. To our interests, complex 1 exhibits interesting semiconductivity and fluorescence properties. When citraconic acid was used instead of maleic acid, a new complex [Cd₂(mesac)₂(1,10′-phen)₂] (2) (mesac = mesaconate dianion) was synthesized under about the same reaction conditions. Complex 2 also exhibits fluorescence properties.