Two exodentate conformations, spectroscopic properties, and Hirshfeld surface analysis of new macrocyclic compounds with tetrabromide and tetraperchlorate

Abstract

• Two novel constrained cyclams with bromides, perchlorates, and hydrates were synthesized and characterized. • Spectral properties of the two compounds were investigated. • Two different exodentate conformations were confirmed by single crystal X-ray diffraction analysis. • Hirshfeld surface analysis was performed to identify the intermolecular interactions. Two novel macrocyclic compounds, [H 4 L ]Br 4 ·4H 2 O ( 1 ) and [H 4 L ](ClO 4 ) 4 ·2H 2 O ( 2 ) [ L = C 22 H 44 N 4 = 3,14‑diethyl-2,6,13,17-tetraazatricyclo(16.4.0.0 7,12 )docosane], were synthesized and characterized by elemental analysis, single-crystal X-ray diffraction, and spectroscopic methods. The asymmetric unit of 1 contains one half of the [H 4 L ] 4+ tetracation, two bromide anions, and two water molecules, while the asymmetric unit of 2 comprises one half of the [H 4 L ] 4+ tetracation, two perchlorate anions, and only one water molecule. The [H 4 L ] 4+ cation of 1 adopts an exodentate [3,4,3,4]- D conformation, while the [H 4 L ] 4+ cation of 2 adopts an exodentate [3,4,3,4]- A conformation. In the crystals of 1 and 2 , the macrocyclic tetracations, water molecules, and bromide and perchlorate anions are held together by N–H⋯O, O—H⋯Br, N–H⋯Br, O–H⋯O and C–H⋯O hydrogen bonds, thus forming a three-dimensional structure. Hirshfeld surface analysis and 2D fingerprint plots reveal that the crystal packing in 1 and 2 is dominated by the H⋯H, Br⋯H/H⋯Br, and O⋯H/O⋯H contacts.