Size-dependent encapsulation selectivity of alkaline earth metal ions in distorted octahedral and dicapped Ni(II) metallacryptate with L-isoleucine

Size-dependent encapsulation selectivity of alkaline earth metal ions in distorted octahedral and dicapped Ni(II) metallacryptate with L-isoleucine Full article

Journal

Journal of Molecular Structure
ISSN: 0022-2860 , E-ISSN: 1872-8014

Output data

Year: 2026, Volume: 1351, Article number : 144164, Pages count : DOI: 10.1016/j.molstruc.2025.144164

Authors

Savarets Alexander R. ¹ , Maximova Anna D. ² , Dolotov Roman A. ¹ , D’yakonov Vladimir A. ¹ , Dolzhenko Vladimir D. ^3,1

Affiliations

1	N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninskii pr., 119991 Moscow, Russian Federation
2	Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninskii pr., 119991 Moscow, Russian Federation
3	Department of Chemistry, M. V. Lomonosov Moscow State University, 1 Lenin’s Hills, 119991 Moscow, Russian Federation

The study of size selectivity of cryptands and crown ethers towards metal ions is one of the most interesting and promising directions in supramolecular chemistry. In this work the metallacryptates [MNi6(Ile)12](ClO4)2 (M = Ba2+, Sr2+; Ile = l-isoleucine) (2–3) and the complex [Ca2Ni6(Ile)12(CH3OH)6(H2O)3](ClO4)4 (4) were synthesized for the first time. The composition and structure of the obtained compounds were studied by single-crystal X-ray diffraction (SCXRD), IR-spectroscopy, CHN analysis, electrospray ionization mass spectrometry (ESI-MS) and energy-dispersive X-ray spectroscopy (EDX). The time-dependent dynamics of self-assembly of metallacryptates 2–3 was investigated by PCA method. The intermediate complex ion [MNi5(Ile)10]2+ was discovered, it coexists in solution together with complexes 2–3. The stability constants of the complexes [MNi6(Ile)12]2+ decrease in the series Ba2+ – Sr2+. It is shown that the class of octahedral Ni(II) metallacryptates with amino acids possesses a rigid [Ni6(AA)12] framework (AA = amino acids) and exhibits very high size and charge selectivity towards the central atom, showing no binding affinity for monovalent cations and Mg2+. Significant changes in the crystal radius across the series of alkaline earth metal ions (M2+) allowed us to investigate the size selectivity of octahedral M(II)-Ni(II) metallacryptates with l-isoleucine. Complexes 2–3 belong to the class of octahedral metallacryptates. The possibility of the existence of 4 was previously denied in the literature. Changes in structural parameters correlate well with the electronic structure, investigated by quantum chemical calculations and UV–Vis spectroscopy within the ligand field theory.

Savarets A.R. , Maximova A.D. , Dolotov R.A. , D’yakonov V.A. , Dolzhenko V.D.
Size-dependent encapsulation selectivity of alkaline earth metal ions in distorted octahedral and dicapped Ni(II) metallacryptate with L-isoleucine
Journal of Molecular Structure. 2026. V.1351. 144164 . DOI: 10.1016/j.molstruc.2025.144164 WOS Scopus OpenAlex

Submitted:	Aug 8, 2025
Published online:	Oct 6, 2025

≡ Web of science:	WOS:001592884600006
≡ Scopus:	2-s2.0-105017627365
≡ OpenAlex:	W4414547405