Delia B. Soria

Synthesis, X-ray crystal structure, thermal behavior and spectroscopic analysis of 1-(1-naphthoyl)-3-(halo-phenyl)-thioureas complemented with quantum chemical calculations.

Two novel 1-(1-naphthoyl)-3-(halo-phenyl) substituted thioureas, namely 1-(1-naphthoyl)-3-(2,4-di-fluoro-phenyl)-thiourea (1) and 1-(1-naphthoyl)-3-(3-chloro-4-fluoro-phenyl)-thiourea (2), were synthesized and fully characterized. The X-ray crystal and molecular structures have been determined resulting in a planar acylthiourea group, with the C=O and C=S adopting a pseudo-antiperiplanar conformation. An intramolecular N-H⋯O=C hydrogen bond occurs between the thioamide and carbonyl groups. The crystal packing of both compounds is characterized by extended intermolecular N-H⋯S=C and N-H⋯O=C hydrogen-bonding interactions involving the acylthiourea moiety. Compound 2 is further stabilized by π-stacking between adjacent naphthalene and phenyl rings. The thermal behavior, as well as the vibrational properties, studied by infrared and Raman spectroscopy data complemented by quantum chemical calculations at the B3PW91/6-311++G(d,p) support the formation of these intra- and intermolecular hydrogen bonds. Furthermore, the UV-Vis spectrum is interpreted in terms of TD-DFT quantum chemical calculations with the shapes of the simulated absorption spectra in good accordance with the experimental data.

A substituted sulfonamide and its Co (II), Cu (II), and Zn (II) complexes as potential antifungal agents

Abstract A sulfonamide 1-tosyl-1-H-benzo(d)imidazol-2-amine (TBZA) and three new complexes of Co(II), Cu(II), and Zn(II) have been synthesized. The compounds have been characterized by elemental analyses, FTIR, 1H, and 13C-NMR spectroscopy. The structure of the TBZA, and its Co(II) and Cu(II) complexes, was determined by X-ray diffraction methods. TBZA and its Co(II) complex crystallize in the triclinic P-1 space group, while the Cu(II) complex crystallizes in the monoclinic P21/c space group. Antifungal activity was screened against eight pathogenic yeasts: Candida albicans (DMic 972576), Candida krusei (DMic 951705), Candida glabrata (DMic 982882), Candida tropicalis (DMic 982884), Candida dubliniensis (DMic 93695), Candida guilliermondii (DMic 021150), Cryptococcus neoformans (ATCC 24067), and Cryptococcus gattii (ATCC MYA-4561). Results on the inhibition of various human (h) CAs, hCA I, II, IV, VII, IX, and XII, and pathogenic beta and gamma CAs are also reported.

Tantalum chloride species incorporating anionic and cationic guanidine components

Attempted preparation of tantalum complexes incorporating the anionic guanidinate ligand derived from 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) are reported. Reaction of (hpp)SiMe3 and TaCl5 in a 1:1 ratio gave the bis-guanidinate compound rather than the expected mono-ligand species. Reaction of 2 equiv. of (hpp)SiMe3 or in situ generated [hpp]Li with TaCl5 afforded a solid which analysed correctly for the compound (hpp)2TaCl3. X-ray structural analysis of the crystallised product identified the coordination isomer [Ta(hpp)4][TaCl6], with a distorted dodecahedral cation and a regular octahedral anion. During the course of this study, two closely related hydrolysis products, [(hppH2)]2[{TaCl6}{Cl}] and [(hppH2)]3[{TaCl6}2{Cl}]eCN were isolated and structurally characterised, each containing [hppH2]+ cations and [Cl]? and [TaCl6]? anions in extended arrays, linked by intermolecular hydrogen bonds.

Crystal and molecular structure determination, TGA-DTA, and infrared and Raman spectra of rubidium nitroprusside, Rb2[Fe(CN)5NO]

The title compound, Rb2[Fe(CN)5NO], crystallizes in the space group P212121, witha=5.687(1),b=15.956(2),c=12.645(3) Å, andZ=4. Anions are in equivalent C1 sites (one per asymmetric unit) and are slightly distorted octahedra (C4v ideal symmetry). TGA and DTA curves and vibrational (infrared and Raman) spectra of Rb2[Fe(CN)5NO] were obtained. Results are interpreted in view of the crystal structure of the compound and the behavior of related substances.

Crystal and molecular structure and photoisomerization of nitropentaamminecobalt(III) nitroprusside sesquihydrate, [Co(NH3)5NO2][Fe(CN)5NO]·1.5H2O

Abstract The crystal structure of nitropentaamminecobalt(III) nitroprusside sesquihydrate, [Co(NH3)5NO2][Fe(CN)5NO]·1.5H2O has been determined by Patterson and Fourier methods employing 3881 independent X-ray reflections with I>2σ(I) and refined by full-matrix least-squares to R1=0.032. The substance crystallizes in the monoclinic C2/c (C2h6) space group No. 15, with a=28.408(3), b=6.422(1), c=22.401(3) A, β=123.55(1)° and Z=8. The metastable state I (MSI) of the nitroprusside anion and the photochemical isomerization reaction of the nitropentaamminecobalt(III) cation to the nitrito isomer were produced by irradiation with Ar+ laser light of 488 nm wavelength at 77 K. TGA and DTA of the non-excited substance were performed under nitrogen atmosphere.

Magnetic properties, infrared spectroscopy, thermal and theoretical studies of oxomolybdenum(V) complexes with 2,2′-bipyrimidine

Mono- and dinuclear complexes of oxomolybdenum(V) with 2,2′-bipyrimidine (bpym), MoOCl3(bpym) (1) as two geometric isomers (violet and brown), Mo2O3Cl4(bpym)2 (2), Mo2O4Cl2(bpym)2 (3), and Mo2O2Cl6(μ-bpym) (4), have been prepared and characterized by EPR, electronic, infrared and Raman spectroscopy, thermal analysis and theoretical calculations. Magnetic susceptibilities in the 4.6–290 K range show different magnetic behavior for the MoO3+, and Mo2O2 (μ-bpym)6+ units. The EPR spectra have also been registered. Theoretical calculations converged to two stable isomers named cis and trans for MoOCl3(bpym), Mo2O3Cl4(bpym)2 and for Mo2O4Cl2(bpym)2 but four isomers for Mo2O2Cl6(μ-bpym). Based on the theoretical and experimental results for the violet and brown 1, we assume that both cis and trans isomers are present in the solid state. This could also explain the existence of two isomers in Mo2O2Cl6(μ-bpym).

Vibrational and 13C NMR spectra and thermal behaviour of sodium pentacyanocarbonilferrate(II) dihydrate, Na3[Fe(CN)5CO] · 2H2O

Abstract Infrared, Raman and 13C NMR spectra of the title compound were obtained. The infrared spectra were recorded at room and low temperatures. TGA-DTA results obtained under oxygen, helium and nitrogen atmospheres are also presented.

Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution

1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1=2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans-cis geometry of the almost planar thiourea unit is stabilized by intramolecular NH⋯OC hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31+G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular NH⋯SC hydrogen bond forming R22(8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S⋯H, O⋯H and H⋯H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.

Infrared and Raman spectra of potassium pentacyanonitrosylmanganate(I) dihydrate: K3[Mn(CN)5NO]· 2H2O

The infrared spectra of polycrystalline K3[Mn(CN)5NO]·2H2O at different degrees of deuteration were recorded between 4000 and 200 cm−1, both at room and low temperature. The room-temperature Raman spectrum of the isotopically normal powder was also obtained. The observed bands were assigned to the internal vibrational modes of the [Mn(CN)5NO]−3 ion and to the internal and librational modes of water of hydration. In accordance with X-ray diffraction studies, the spectra showed the existence of two crystallographically distinct types of water molecules located in different sets of sites ofC1 symmetry.

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

Functionalized silica nanoparticles (NP) were obtained by esterification of the silanol groups of fumed silica nanoparticles with benzyl alcohol. These particles were characterized by Fourier transform infrared spectroscopy, 13C and 29Si NMR spectroscopy, thermogravimetry, total organic carbon, Brunauer–Emmett–Teller analysis, UV‐visible spectroscopy, and transmission electron microscopy. NP suspensions in water/acetonitrile mixtures were used as quenchers of benzophenone (BP) phosphorescence in time‐resolved experiments at the excitation wavelength of 266 nm. The phosphorescence signals obtained in the presence of the nanoparticles were fitted to biexponential decays. Both decays were accelerated in the presence of increasing amounts of NP. A model, including the reversible adsorption of BP on the NP, which was supported by computer simulations accounts for the observed results. Laser flash‐photolysis experiments with excitation at 266 nm of NP suspensions in water/acetonitrile in the presence of BP generated benzyl radicals that were attached to the silica surface. These radicals were detected at their absorption maxima (320 nm) by transient optical techniques.