Co(II)-amino acideCaAl-layered double hydroxide composites e Construction and characterization G  abor Varga a, b , Zolt  an K  onya c, d ,  Akos Kukovecz c ,P  al Sipos b, e , Istv  an P  alink  o a, b, * a Department of Organic Chemistry, University of Szeged, D om ter 8, Szeged, H-6720, Hungary b Materials and Solution Structure Research Group, Institute of Chemistry, University of Szeged, Aradi Vertanúk tere 1, Szeged, H-6720, Hungary c Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Bela ter 1, Szeged, H-6720, Hungary d MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Rerrich Bela ter 1, Szeged, H-6720, Hungary e Department of Inorganic and Analytical Chemistry, University of Szeged, D om ter 7, Szeged, H-6720, Hungary article info Article history: Received 24 September 2018 Received in revised form 7 November 2018 Accepted 8 November 2018 Available online 9 November 2018 Keywords: CaAl-layered double hydroxide Co(II)-Amino acid complexes Intercalation Structural characterization abstract The construction of Co(II)-amino acid complexes (L-histidine, L-cysteine, L-tyrosine) among the layers of CaAl-layered double hydroxide was attempted. The stepwise intercalation (introducing the anionic form of the amino acid first, then constructing the Co(II) complex) proved to be unsuccessful, while the direct ion exchange of the anionic form of the separately prepared complex provided with the Co(II) complex intercalated substances. The success of the intercalation was verified by X-ray diffractometry. The resulting composite materials were structurally characterized by a range of instrumental methods like UVevis, inductively coupled plasmaeoptical emission, mid-range as well as far infrared spectroscopies and scanning electron microscopy. © 2018 Elsevier B.V. All rights reserved. 1. Introduction In recent years, layered double hydroxides (LDHs) have been receiving increased attention in many groups working in diverse fields [1e5]. Significant progress in the synthesis of LDHs with new compositions and morphologies was made [6e10]. These materials have fascinating properties, such as the ease of preparation, ability to intercalate various anions, tendency to protect intercalated an- ions from physicochemical degradation and controlled release of intercalated anions [11], etc. Layered double hydroxides have ver- satile applications in wide range of areas including catalysis [12e14], photochemistry [15e17], electrochemistry [18,19], biomedicine [1,20], magnetization [21] and environmental pro- tection [22]. The use of layered inorganic solids as frameworks for the con- struction of inorganic-organic host-guest supramolecular struc- tures is of increasing interest. A particular class of LDHs is the one, in which the interlayer anion is an organic molecule in anionic form. Organic anions intercalated into the inorganic host structures of LDHs are considered to be a class of inorganic-organic hybrid compounds [23]. The properties of such LDHs, their characteriza- tion and applications were reviewed recently, in particular, their use as additives in polymers, precursors to magnetic materials, and in biology and medicine [24]. In the experimental work leading to this contribution, inorganiceorganic hybrid materials were synthesized, in which the host material was CaAl-LDH, and the guest anions were the Co(II) complexes of L-histidine, L-tyrosine or L-cysteine, in anionic form. The substances obtained were characterized by various instru- mental methods. To the best of our knowledge, substances like these have never been the subject of experimental scrutiny before. Moreover, this work can be considered to be the extension of a previous work, in which Co(II)-amino acid complexes using the same amino acids as in this contribution, but in C-protected form, were anchored to modified silica gel [25]. In the original consid- erations these amino acids were chosen because they often occur around the metal ion sites in various metalloenzymes like super- oxide dismutase, etc. [26]. * Corresponding author. Department of Organic Chemistry, University of Szeged, D om t er 8, Szeged, H-6720, Hungary. E-mail address: palinko@chem.u-szeged.hu (I. P alink o). Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: http://www.elsevier.com/locate/molstruc https://doi.org/10.1016/j.molstruc.2018.11.032 0022-2860/© 2018 Elsevier B.V. All rights reserved. Journal of Molecular Structure 1179 (2019) 263e268 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by SZTE Publicatio Repozitórium - SZTE - Repository of Publications