Tetraphenylmethane and tetraphenylsilane as building units of coordination polymers and supramolecular networks – A focus on tetraphosphonates

Abstract

In this work are explored opportunities for supramolecular and coordination chemistry that arise from a combination of a phosphonic functional group with tetrahedrally-shaped aromatic units: tetraphenylmethane (TPM) and tetraphenylsilane (TPSi). To provide a complete overview of TPM and TPSi-based tetraphosphonate materials, this paper has been divided into three distinct parts. In the first part are brought together and evaluated most convenient synthetic methods that can be employed for the preparation of TPM and TPSi aromatic scaffolds and of their corresponding tetrabromo derivatives (TPM-Br4 and TPSi-Br4). Further, possible routes to tetrakis(4-phosphonophenyl)methane (TPPM) and tetrakis(4-phosphonophenyl)silane (TPPSi) are discussed, with particular attention being paid to the palladium and nickel-catalyzed phosphonylation reactions. The second part of the literature survey is devoted to the overview of useful functionalities of metal-organic frameworks (MOFs) and coordination polymers (CPs) based on TPPM and TPPSi. This part starts with the description of various crystal engineering approaches towards the preparation of porous metal phosphonates – a rare class of materials that combines gas sorption property and exceptional thermal and chemical resistance. Next, copper(II) and zirconium phosphonates constructed from TPPSi are highlighted as robust heterogenous catalysts for cycloaddition of carbon dioxide to epoxides and epoxide ring-opening reactions. Further, TPPM-based diester CPs with cobalt(II) ions have been investigated in terms of their nonlinear optical properties, serving as models for studies of spectrally-resolved second harmonic generation (SHG) and third harmonic generation (THG). In the third, final part of this work are overviewed efforts of several research groups on the elucidation of solid-state assembly and supramolecular chemistry of TPPM and TPPSi tectons. Here, the emphasis is being placed on their packing preferences, hydrogen bonding, Hirshfeld surface properties and phenyl embrace interactions.