Anion-directed supramolecular assembly of cobalt(II)-fluconazole coordination polymers: Structural diversity, fluorescent and magnetic properties

Six fluconazole-bridged cobalt(II) coordination polymers, namely [Co(HFlu)2(H2O)2](ClO4)2 (1), [Co(HFlu)2(H2O)(AcO)](AcO)·2C2H5OH (2), [Co(HFlu)2Cl2]·2C2H5OH (3), [Co3(Flu)2(acac)4]·C2H5OH (4), [Co(HFlu)2(malo)(H2O)]·3H2O (5), and [Co(HFlu)2(fum)(H2O)2]·H2O (6) (HFlu = 2-(2′,4′-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-2-ol, AcOH = acetate acid, Hacac = acetylacetonate, H2malo = malonate acid, H2fum = fumaric acid), have been synthesized and structurally characterized, and the thermal, fluorescent and magnetic properties investigated. The crystal structures display the one-dimensional cationic double-bridged chain consisting of 20-membered macrocycles to be parallel in 1 and perpendicular in 2. The structure of 3 consists of two-dimensional neutral rhombic grid in bc plane with (4,4) topology and alternative P/M helices intersecting at the Co sites along b direction. Complex 4 shows one-dimensional polymeric chain, in which binuclear Co2(Flu)2(acac)2 units act as bridging blocks to link Co(acac)2 nodes through triazolyl nitrogen atoms. The structure of 5 shows dimeric 20-membered macrometallacyclic motif. Complex 6 shows HFlu-bridged one-dimensional chain, which is stabilized by hydrogen-bonding interactions to produce alternative hydrophobic and hydrophilic architecture. Complexes 1–3 and 5–6 exhibit the similar electronic absorption and fluorescent spectra as those of HFlu, while complex 4 shows a fluorescent quenching phenomenon. Fluorescence titration of HFlu suggests that the fluorescent intensities at the maximal emission decrease upon the addition of Co(acac)2. The variable-temperature magnetic measurement of 4 reveals weak ferromagnetic interaction combined with the spin–orbit coupling effect in the 1-D Co(II) chain.