Hexahalorhenate(iv) salts of protonated ciprofloxacin: antibiotic-based single-ion magnets. Issue 48 (17th November 2021)

• Record Type: Journal Article
• Authors: Sanchis-Perucho, Adrián; Orts-Arroyo, Marta; Camús-Hernández, Javier; Rojas-Dotti, Carlos; Escrivà, Emilio; Lloret, Francesc; Martínez-Lillo, José
• Is Part Of: CrystEngComm. Volume 23:Issue 48(2021)
• Page Start: 8579
• Page End: 8587
• Publication Date: 2021-11-17
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d1ce01337h
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : In the crystal lattice of two novel Re IV compounds, the paramagnetic [ReCl6 ] 2− and [ReBr6 ] 2− anions are well separated from each other through two protonated forms of the antibiotic ciprofloxacin. These compounds behave as single-ion magnets (SIMs). Abstract : Two novel Re IV compounds of formula [H2 cip][Hcip][ReCl6 ]Cl·H2 O (1 ) and [Hcip]2 [ReBr6 ] (2 ) [(H2 cip) 2+ /(Hcip) + = ciprofloxacindiium cation/ciprofloxacinium cation] have been synthesized and studied structurally and magnetically. 1 crystallizes in the monoclinic system with space group P 21 / c, whereas 2 crystallizes in the orthorhombic system with space group Pbca. 1 and 2 are hexahalorhenate(iv ) salts obtained with the protonated ciprofloxacin antibiotic. In their crystal lattice, the [ReX6 ] 2− [X = Cl(1 ) and Br(2 )] anions are well separated from each other through the protonated ciprofloxacindiium (1 ) and ciprofloxacinium (1 and 2 ) cations, which are arranged without generating intermolecular Re−X⋯X−Re interactions between the paramagnetic centers. In both compounds, intermolecular π⋯π (1 ) and π⋯F (2 ) type interactions [the shortest centroid⋯centroid and centroid⋯fluorine distance being approximately 3.49(1) and 2.95(1) Å, respectively], as well as hydrogen bonds (1 and 2 ), are present. The self-assembly of these protonated organic cations and Re IV complexes generate novel supramolecular structures based on this paramagnetic 5d metal ion. The study of their magnetic properties through variable-temperature dc magnetic susceptibility measurements reveals a magnetic behaviour typical of noninteracting mononuclear Re IV complexes ( S Re = 3/2), with magnetically isolated spin quartets and high values of their zero-field splitting (ZFS), for 1 and 2 . In addition, AC magnetic susceptibility measurements in the presence of external dc fields show slow relaxation of the magnetization, which is a behavior compatible with the occurrence of the field-induced single-ion magnet (SIM) phenomenon for 1 and 2 . This is the first magnetostructural study performed on salts based on protonated ciprofloxacin antibiotic and a paramagnetic 5d ion.