Location controlled symmetry reduction: Paradigm of an open metalloporphyrin framework based on the tetracarboxy porphyrin linker

Location controlled symmetry reduction of the tetracarboxy porphyrin linker by altering the position of the coordinating groups leads to the design of a novel reduced symmetry linker 5,15-bis(p-carboxyphenyl)-10,20-bis(m-carboxyphenyl)porphyrin (H₄-TpmCPP). The corresponding crystalline coordination framework Gd-TpmCMPF was synthesized by employing the NaOH modulator approach. The resulting compound is an 8-connected network with a bcu topology and two different perforated 1D channels. The consequence of reduced symmetry is highlighted in the geometry of capsular void spaces formed between porphyrin moieties in the framework which allows coordination with formate ions in the reaction mixture.