Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Synthesis, X-ray crystal structure, thermal behavior and spectroscopic analysis of 1-(1-naphthoyl)-3-(halo-phenyl)-thioureas complemented with quantum chemical calculations
Graphical abstract
Introduction
Increasing attention is devoted to the structural and conformational elucidation of 1-(acyl/aroyl)-3-(mono-substituted) thiourea derivatives since these properties mostly determine the behavior of these compounds as ionophores for ion selective electrodes [1], [2], [3], [4] and chemosensors for naked-eye recognition of anions [5], [6], [7], [8]. In particular, the thiourea molecule and the acceptor anion participate in hydrogen bond interactions [9], playing also an important role in terms of biological activity displayed by these compounds [10]. It is well-documented [11] that a local planar structure of the C(O)NHC(S)NH moiety is preferred for 1-(acyl/aroyl)-3-(mono-substituted) thiourea, with opposite orientation between the CO and CS double bonds (“S-shape”) [12]. A pseudo six-membered ring is formed in this conformation, associated with the promotion of a CO⋯HN intramolecular hydrogen bond [13].
Several reports on 1-acyl-3-naphtyl substituted thiourea derivatives can be found in the literature [14], [15], [16], [17], [18], [19]. Less attention, however, has been received by the isomeric 1-(naphtoyl)-3-substituted thiourea compounds (see Scheme 1). A series of 1-(naphthoyl)-3-mono substituted and 3,3-di-substituted thioureas were synthesized by Dzurilla et al. [20] and their behavior toward the oxidation with Br2 in chloroform (Hugershoff reaction) was determined. The capabilities of (1-naphtlyl)-arylamidine compounds as ligand were investigated and their CuII-, NiII- and PdII-complexes have been prepared [21]. In these complexes, the anionic O,S bis-chelate coordination mode was found and near-square-planar geometries around the central metal with a cis arrangement was determined [21]. Di-thiourea derivatives substituted by 2-naphthoyl groups were also structurally characterized [22].
Continuing our ongoing project aimed to the synthesis of 1-(acyl/aroyl)-3-(mono-substituted) thioureas [23], [24], here we report the preparation and spectroscopic characterization of two closely related thioureas having the 1-(1-naphthoyl) group and 3-(2,4-di-fluoro-phenyl) (1) and 3-(3-chloro-4-fluoro-phenyl) (2) substitution. The crystal structures have been determined by single-crystal X-ray diffraction. Their NMR, mass spectra, infrared and Raman and UV–Vis spectroscopic properties were also discussed. The assignment of the bands was accomplished with the aid of quantum chemical calculations. The thermogravimetric studies were analyzed.
Section snippets
Instrumentation
Melting points were recorded using a digital Gallenkamp (SANYO) model MPD.BM 3.5 apparatus and are uncorrected. 1H NMR and 13C NMR spectra were determined in DMSO-d solution at 300 and 75.5 MHz respectively using a Bruker AM-300 spectrophotometer. Mass Spectra (EI, 70 eV) were taken on a GC–MS, Agilent technologies 6890 N with an inert mass selective detector 5973 mass spectrometer and elemental analyses were conducted using a LECO-183 CHNS analyzer.
Fourier transform infrared spectroscopy (FTIR),
Synthesis and characterization
The synthetic pathway is shown in the Scheme 2. 1-Naphthoyl chloride was freshly prepared from the commercial 1-naphthoic acid according to the standard procedure [37] and added to a solution of potassium thiocyanate in dry acetone to obtain the 1-naphthoyl isothiocyanate as an intermediate via stirring at room temperature followed by the reflux. The latter was separately reacted with 2,4-difluoro- and 3-chloro-4-fluoro-anilines to afford the corresponding thioureas as crude solids.
Conclusion
The conformational and structural properties have been determined for two novel 1-(1-naphthoyl)-3-(halo-phenyl) substituted thioureas. The X-ray molecular structures for both compounds here studied show that the central C(O)NHC(S)NH moiety adopts the typical six membered ring structure favored by strong CO⋯HN intramolecular hydrogen bond. Intermolecular NH⋯O and NH⋯S hydrogen bond interactions dominate the crystal packing of 1 and 2. Furthermore, a π-stacking interaction between adjacent
Acknowledgments
MFE and DBS are members of the Carrera del Investigador of CONICET (República Argentina). The Argentinean author thanks to the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), the ANPCYT and to the Facultad de Ciencias Exactas, Universidad Nacional de La Plata for financial support.
References (63)
- et al.
Could N-(diethylcarbamothioyl)benzamide be a good ionophore for sensor membranes?
J. Mol. Struct.
(2010) - et al.
Lead(II) ion selective electrodes with PVC membranes based on two bis-thioureas as ionophores: 1,3-bis(N′-benzoylthioureido)benzene and 1,3-bis(N′-furoylthioureido)benzene
J. Hazard. Mater.
(2010) - et al.
A Raman and infrared study of 1-furoyl-3-monosubstituted and 3,3-disubstituted thioureas
Spectrochim. Acta A
(2005) - et al.
Aroylthioureas: new organic ionophores for heavy metal ion selective electrodes. A nuclear magnetic resonance study
Spectrochim. Acta A
(2002) - et al.
Novel salicylic acid-oriented thiourea-type receptors as colorimetric chemosensor: synthesis, characterizations and selective naked-eye recognition properties
Spectrochim. Acta A
(2012) - et al.
Competing intramolecular NH⋯OC hydrogen bonds and extended intermolecular network in 1-(4-chlorobenzoyl)-3-(2-methyl-4-oxopentan-2-yl) thiourea analyzed by experimental and theoretical methods
Chem. Phys.
(2014) - et al.
The molecular structure and vibrational spectra of N-(2,2-diphenylacetyl)-Ń-(naphthalen-1yl)-thiourea by Hartree–Fock and density functional methods
Spectrochim. Acta A
(2009) - et al.
Synthesis, structural and vibrational properties of 1-(4-Fluorobenzoyl)-3-(isomeric fluorophenyl)thioureas
J. Mol. Struct.
(2011) - et al.
Vibrational spectra of monothiocarbamates-II. IR and Raman spectra, vibrational assignment, conformational analysis and ab initio calculations of S-methyl-N, N-dimethylthiocarbamate
Spectrochim. Acta A
(1993) Vibrational energy distribution analysis (VEDA): scopes and limitations
Spectrochim. Acta A
(2013)