Investigation of structural, optical and electrical conductivity of a new organic inorganic bromide: [C12H17N2]2ZnBr4.

A new organic-inorganic hybrid, namely the [C12H17N2]2ZnBr4 compound, has been synthesized and studied by single-crystal X-ray diffraction and optical and complex impedance spectroscopy. It crystallized in the centrosymmetric P21/n space group at room temperature. The asymmetric unit is constituted by [ZnBr4]2- anions, showing slightly distorted tetrahedral geometry, surrounded by four organic (C12H17N2)+ cations. The crystal packing is stabilized by N-H⋯Br and C-H⋯Br hydrogen bonds arranged in a three-dimensional network. The optical absorption measurement confirms the semiconductor nature with a band gap of around 3.94 eV. Additionally, the analysis of Nyquist plots (-Z'' vs. Z') shows that the electrical properties of the material are heavily dependent on frequency and temperature, indicating a relaxation phenomenon and semiconductor-type behavior. Reduction in Z' was observed as a function of temperature and frequency which indicates an increase in ac conductivity and the negative temperature coefficient of resistance. The frequency dependent plots of (-Z'') show that the electrical relaxation is non-Debye in nature. The ac conductivity spectrum obeys Jonscher's universal power law. The Correlated barrier hopping model CBH has been suggested to agree with the conduction mechanism of σ ac for the [C12H17N2]2ZnBr4 compound.

Minor histocompatibility antigens in Tunisians: could platelet endothelial cell adhesion molecule 1 marker be one of them?

Platelet endothelial cell adhesion molecule 1 (PECAM-1/CD31) is one of the human minor histocompatibility antigens that are the main targets of alloreactive T-cells after hematopoietic stem cells or solid organs transplantation. In order to investigate its polymorphism in Tunisians, three single nucleotide polymorphisms (SNPs) (rs668, rs12953 and rs1131012) were selected to perform an allele and haplotype analysis. Hundred-and-forty-two healthy and unrelated subjects were enrolled in this survey. Genomic DNAs were extracted using salting out method. SNP genotyping assays were performed with home-designed sequence-specific primers polymerase chain reaction (SSP-PCR). As a result, molecular analysis showed that PECAM-1 is one of the most polymorphic markers in the Tunisian population because minor allele frequency was 0.3, and minimum haplotype frequency was 0.03. A low linkage disequilibrium (D' = 0.45) between rs12953 and rs1131012 was noticed, although all other loci were in the Hardy-Weinberg equilibrium (minimum P value = 0.07). The frequencies were close to those reported in African-American and Caucasian groups.

HA-1 and HA-2 minor histocompatibility antigens in Tunisians.

Minor histocompatibility antigens (MiHAgs), such as HA-1 and HA-2, are the main targets of immune responses after allogeneic stem cell transplantation (SCT). HA-1 and HA-2 are two hematopoietic system-restricted antigens encoded, respectively, by HMHA1 and MYO1G genes. In order to estimate their frequencies in Tunisians, we performed a molecular-based allele analysis for 160 healthy and unrelated subjects. Genomic DNAs were extracted mainly by the salting out method. Single nucleotide polymorphism (SNP) genotyping assays for selected sites at HMHA1 gene (rs3764653 and rs1801284) and at MYO1G gene (rs61739531) were performed with a sequence specific primers-polymerase chain reaction (SSP-PCR) method. Statistical analysis of our results showed that the HA-2 antigen is more frequent than the HA-1 antigen in the Tunisian population because their frequencies were 97% and 57%, respectively. Allele analysis for HMHA1 gene showed that the R variant (500T-504G) was predominant in our population (64%). For the MYO1G gene, the C allele was predominant (84%). All loci were in Hardy-Weinberg equilibrium (minimum P value = 0.06). Our frequencies were close to those reported in African and Caucasian groups.

Additional Tunisian patients with Sanjad-Sakati syndrome: A review toward a consensus on diagnostic criteria.

BACKGROUND AND OBJECTIVES: Sanjad-Sakati syndrome (SSS; OMIM 241410) is a rare autosomal recessive disorder found almost exclusively in people of Arab origin. It is characterized by congenital hypoparathyroidism, severe prenatal and postnatal growth retardation, and distinct facial dysmorphism. The molecular pathology of this syndrome was shown to be due to a mutation in the tubulin-specific chaperone E (TBCE) gene in chromosomal area 1q42-q43. We aimed to detect and confirm the common mutation responsible for SSS in Tunisian patients and review the literature in order to create a set of clinical diagnostic criteria that might provide appropriate indications for molecular testing. METHODS: Three Tunisian patients with clinical feature of SSS were examined via direct Sanger sequencing of exon 3 of the TBCE gene. RESULTS: Mutation analysis of the TBCE gene revealed the common 12-bp (155-166del) deletion in three new patients, thus raising the number of reported SSS patients to 73. Reviewing the literature, we suggest a scoring system that assigns one point each for major criteria and one half point for minor criteria. INTERPRETATION AND CONCLUSIONS: SSS is an autosomal recessive disorder found in the Middle Eastern population with an estimated incidence of 1 per 40,000-100,000 live births in Saudi Arabia. Reviewing the literature on both its clinical and biochemical characteristics, we suggest for the first time, based on defined major and minor SSS criteria, a clinical scoring system for the diagnosis of SSS. On the one hand, an established scoring system will provide appropriate indications for molecular testing and, on the other hand, reviewed data on SSS will help delineate the phenotype and draw a distinction between differential diagnoses.

DFT computations on: Crystal structure, vibrational studies and optical investigations of a luminescent self-assembled material.

The current work undertakes the growth and the physicochemical properties of a novel green-yellow luminescence semi-organic material, the 3-picolylammonium bromide abbreviated (Pico-Br). In this paper, we report the X-ray diffraction measurements which show that the crystal lattice consists of distinct 3-picolylammonium cations and free bromide anions connected via NH⋯Br and NH⋯N hydrogen bonds leading to form a two dimensional frameworks. Molecular geometry compared with its optimized counterpart shows that the quantum chemical calculations carried out with density functional method (DFT) well produce the perceived structure by X-ray resolution of the studied material. To provide further insight into the spectroscopic properties, additional characterization of this material have been performed with Raman and infrared studies at room temperature. Theoretical computations have been computed using the (DFT) method at B3LYP/LanL2DZ level of theory implemented within Gaussian 03 program to study the vibrational spectra of the investigated molecule in the ground state. Optical absorption spectrum inspected by UV-visible absorption reveals the appearance of sharp optical gap of 280nm (4.42eV) as well as a strong green photoluminescence emission at 550nm (2.25eV) is detected on the photoluminescence (PL) spectrum at room temperature. Using the TD/DFT method, HOMO-LUMO energy gap and the Mulliken atomic charges were calculated in order to get an insight into the material. Good agreement between the theoretical results and the experimental ones was predicted.

Synthesis, crystal structure, vibrational spectroscopy, optical properties and theoretical studies of a new organic-inorganic hybrid material: [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2.

A new organic-inorganic hybrid material, [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2, has been synthesized and characterized by X-ray diffraction, FT-IR, Raman spectroscopy and UV-Visible absorption. The studied compound crystallizes in the triclinic system, space group P1¯ with the following parameters: a=8.4749(6)(Å), b=17.1392(12)(Å), c=17.1392(12)(Å), α=117.339(0)°, ß=99.487(0)°, γ=99.487(0)° and Z=2. The crystal lattice is composed of a two discrete (BiBr6)(3-) anions surrounded by six ((CH3)2NH2)(+) cations. Complex hydrogen bonding interactions between (BiBr6)(3-) and organic cations from a three-dimensional network. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure, vibrational spectra and optical properties of the investigated molecule in the ground state. The full geometry optimization of designed system is performed using DFT method at B3LYP/LanL2DZ level of theory using the Gaussian03. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from FT-IR and Raman spectra are assigned based on the results of the theoretical calculations. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental UV-Visible spectrum. The results show good consistent with the experiment and confirm the contribution of metal orbital to the HOMO-LUMO boundary.

Structural, vibrational and DSC investigations of the bis-4-benzyl piperidinium tetraoxoselenate monohydrate crystal.

A new organic-inorganic salt, bis-4-benzyl piperidinium tetraoxoselenate monohydrate has been synthesized and characterized by X-ray diffraction, FT-IR and FT-Raman spectroscopies. The title compound crystallizes in the monoclinic system P2(1)/c at room temperature with the following parameters: a=8.617(3)Å, b=27.140(9)Å, c=10.926(5)Å, ß=96.46(4)° and Z=4. Its vibrational spectra have been discussed on the basis on quantum chemical density theory (DFT) calculation using B3LYP/6-31G(*) approach. The role of the intermolecular interaction in this crystal is analyzed. Acidic protons of the selenate group were transferred to the organic cation giving the singly-protonated cation. The ability of ions to form spontaneous three-dimensional structure through O-H···O and N-H···O hydrogen bond is fully utilized. These hydrogen bonds give notable vibrational effects.

Vibrational spectra and non linear optical proprieties of L-histidine oxalate: DFT studies.

This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a nonlinear optical material L-histidine oxalate. Due to the lack of sufficiently precise information on geometric structure in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of L-histidine oxalate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P2(1)2(1)2(1) of orthorhombic system. The FT-IR and Raman spectra of L-histidine oxalate were recorded and analyzed. The vibrational wave numbers were examined theoretical with the aid of Gaussian98 package of programs using the DFT//B3LYP/6-31G(d) level of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied compound. The geometrical parameters of the title compound are in agreement with the values of similar structures. To investigate microscopic second order non-linear optical NLO behaviour of the examined complex, the electric dipole µ(tot), the polarizability α(tot) and the hyperpolarizability ß(tot) were computed using DFT//B3LYP/6-31G(d) method. According to our calculation, the title compound exhibits non-zero ß(tot) value revealing microscopic second order NLO behaviour.

Crystal studies, vibrational spectra and non-linear optical properties of L-histidine chloride monohydrate.

This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a non-linear optical material L-histidine chloride monohydrate. Due to the lack of sufficiently precise information on geometric parameters available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of L-histidine chloride monohydrate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro-symmetric space group P2(1)2(1)2(1) of orthorhombic system. IR spectrum has been recorded in the range [400-4000 cm(-1)]. All the experimental vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using DFT//B3LYP/6-31G (d) method show a good agreement with the experimental data. The calculated vibrational spectra are in well agreement with the experimental one. To investigate microscopic second-order non-linear optical NLO behavior of the examined complex, the electric dipole mu, the polarizability alpha and the hyperpolarizability beta were computed using DFT//B3LYP/6-31G (d) method. The time-dependent density functional theory (TD-DFT) was employed to descript the molecular electron structure of the title compound using the B3LYP/6-31G (d) method. According to our calculations, L-histidine chloride monohydrate exhibits non-zero beta value revealing microscopic second-order NLO behavior.