TIMPZ: an exquisite building block for metal/hydrogen coordination polymers

The novel polynitrogenated ligand tetra-[4(5)-imidazoyl]pyrazine (TIMPZ, 1) and its pincer complex of Fe-II are described. This ligand has an outstanding ability to aggregate in 1D-superstructures by means of hydrogen bonding or metal chelation. TIMPZ shows an unprecedented conformational control over the supramolecular assembly. Metal or hydrogen coordination switches the conformation of peripheral rings driving the assembly preferences. For [Fe-n(TIMPZ)(n+1)](2n+) complexes, UV/Vis spectroscopy shows a bathochromic shift of the main visible absorption band with higher n values. TIMPZ also has hydrogen-bond triggered excited-state intramolecular proton transfer (ESIPT) fluorescence, which is completely inhibited by chelation with transition metals20191722912294FAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo14/25770‐