Transition Metals Coordination by Bis-imidazole-calix[4]arene Ligands with and Without Pyrene Units Grafted at the Large Rim

Nikšić-Franjić, Ivana; Pavlović Saftić, Dijana; Smrečki, Vilko; Colasson, Benoit; Reinaud, Olivia; Piantanida, Ivo; Višnjevac, Aleksandar (2024) Transition Metals Coordination by Bis-imidazole-calix[4]arene Ligands with and Without Pyrene Units Grafted at the Large Rim. International Journal of Molecular Sciences, 25 (20). ISSN 1422-0067

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Abstract

Herein, the presented results show that previously studied DNA/RNA-interacting bis-imidazole-calix[4]arene systems can, in aqueous solutions, efficiently bind a series of biorelevant transition metal cations by coordination with the two imidazole arms at the small rim of their macrocyclic basket. The SCXRD and NMR results structurally characterised the complexes formed by referent bis-imidazole-calix[4]arene with Cu2+ and Zn2+. In solid-state (crystal), the bis-anilino derivative/Cu2+ complex, only upon exposure to the air, undergoes intramolecular dehydrogenative coupling of two neighbouring aniline units, yielding an azo bridge at the large rim of the calix[4]arene basket. In the biorelevant aqueous solution, the comparison of fluorometric titrations of referent calix[4]arene, with its analogues having one or two pyrene units grafted at the opposite (large) rim, revealed moderate-to-strong affinity towards transition metal cations, and, more importantly, a strong impact of pyrene on the binding affinity towards some cations. The pyrene arm(s) significantly diminished the affinity of the calix[4]arene-imidazole ligand towards Cu+ and strongly increased the affinity towards divalent Co2+ and Cd2+ cations. Moreover, the fluorometric response of some studied derivatives was strappingly sensitive to cation type. Since the counter-anion plays only a marginal role, such a change in selectivity is attributed to the intramolecular interaction of pyrene(s) with the calix[4]arene-imidazole system, sterically controlling the metal cation binding site.

Item Type:	Article
Uncontrolled Keywords:	calix[4]arene; pyrene excimer/exciplex; metal coordination; X-ray structures; fluorescence; dehydrogenative coupling
Subjects:	NATURAL SCIENCES > Chemistry
Divisions:	Division of Organic Chemistry and Biochemistry Division of Physical Chemistry NMR Center
Projects:	Project title Project leader Project code Project type Biomimetički “funnel” i “bowl” supramolekularni sustavi za selektivno prepoznavanje DNA/RNA-CALIXDNA / CALIXDNA Aleksandar Višnjevac IP-2020-02-3786 HRZZ
Depositing User:	Lorena Palameta
Date Deposited:	07 Nov 2024 08:45
URI:	http://fulir.irb.hr/id/eprint/9251
DOI:	10.3390/ijms252011314

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