Studying fluorous interactions in a series of coordination compounds derived from mono-pyridyl ligands equipped with hydrogen bonding functionality: exploiting anion⋯πF interaction in separating ClO4− anion from a competing mixture of anions

Abstract

A series of coordination compounds (both coordination complexes (CCs) and coordination polymers (CPs)) viz. [Cu(L1)₄·(SO₄)·(DMSO)]CC1, [(H₂O)₂(DMSO)Cd(L1)₂(μ₂SO₄)(Cd(L1)₂·(SO₄)·(DMSO)·(H₂O)] CC2, [Cu(L2)₂(H₂O)·(Cl)₂] CC3, [Cu(L2)₂(μ-SO₄)(H₂O)]_∝ CP1, [{Cu(L2)₄(μ-SiF₆)}·3H₂O]_∝ CP2, [{Cu(L3)₄(ClO₄)}·ClO₄·H₂O]·CC4, [{Cu(L3)₄(H₂O)}·H₂O·2BF₄] CC5, [{(Cl)Cu(L3)₄(μ-Cl)Cu(L3)₄}·Cl·H₂O] CC6, [{Cu₂(L3)₄(μ-Cl)₂·(Cl)₂}·H₂O] CC7, [Cu(L3)₂(Cl)₂] CC8, and [{Cu(L4)₄·(H₂O)₂}·SO₄·5H₂O] CC9 derived from ligands equipped with pyridyl and pentafluorophenyl/phenyl moieties along with hydrogen bonding backbone (amide/urea) with Cu^II/Cd^II metal centers have been synthesized and characterized by single crystal X-ray diffraction (SXRD). Their various fluorous interactions along with hydrogen bonding have been investigated. The results show that almost all the coordination compounds except CC9 studied herein display various fluorous interactions; in one such example i.e. in CC4, anion–π_F along with other supramolecular interactions (F⋯F, C–H⋯F) shapes the supramolecular assembly, which is exploited to separate environmentally relevant perchlorate anion from a competing mixture of anions viz. SO₄²⁻, NO₃⁻, ClO₄⁻, BF₄⁻, Cl⁻ by following in situ synthesis of the corresponding coordination compound.