INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 18 (2006) 9871–9880 doi:10.1088/0953-8984/18/43/009 Spectroscopic and magnetic properties of a gadolinium macrobicyclic complex G Leniec 1,4 , S M Kaczmarek 1 , J Typek 1 , B Kolodziej 2 , E Grech 2 and W Schilf 3 1 Institute of Physics, Szczecin University of Technology, Aleja Piastow 17, 70-310 Szczecin, Poland 2 Department of Inorganic and Analytical Chemistry, Szczecin University of Technology, Aleja Piast´ ow 42, 70-310 Szczecin, Poland 3 Institute of Organic Chemistry, Polish Academy of Sciences, ulica Kasprzaka 44/52, 01-224 Warsaw, Poland E-mail: taran@ps.pl Received 15 August 2006, in final form 22 September 2006 Published 13 October 2006 Online at stacks.iop.org/JPhysCM/18/9871 Abstract As a result of Schiff base condensation, gadolinium cryptate has been synthesized and investigated by infrared (IR) spectroscopy and electron paramagnetic resonance (EPR) technique. Comparison of IR bands in a ligand and the gadolinium complex confirmed the formation of the gadolinium cryptate complex. IR and thermogravimetry-differential thermal analysis (TG-DTA) analyses indicate the presence of two water molecules in the inner sphere of the complex. Mass spectroscopy investigations confirmed a monometallic substitution of the Gd 3+ ion into the macrobicycle ligand. EPR spectra of the complex have been registered in the 3–300 K temperature range. Each spectrum has been simulated using the EPR–NMR computer program and the values of the spin Hamiltonian parameters at each temperature have been calculated. The thermal dependence of the spin Hamiltonian parameters has been investigated. The temperature dependence of the integrated intensity of the EPR spectrum revealed the magnetic interactions in the spin system of this compound. No long-range magnetic order has been detected in the 3–300 K range, but a strong antiferromagnetic interaction in the high-temperature range, above 160 K, has been observed. 1. Introduction The macrobicyclic compounds are interesting because of their ability to form complexes with transition metal ions and rare earths. The design and synthesis of macrobicyclic ligands and their lanthanide complexes are important in applied chemistry, biochemistry and technology. 4 Author to whom any correspondence should be addressed. 0953-8984/06/439871+10$30.00 © 2006 IOP Publishing Ltd Printed in the UK 9871