Molecules Ia Research Articles

CRYSTAL AND MOLECULAR STRUCTURE OF THE ISLAND TETRANUCLEAR DIOXOMOLYBDENUM(VI) COMPLEX [MoO<sub>2</sub>(<i>L</i><sup>1</sup>)]<sub>4</sub> (H<sub>2</sub><i>L</i><sup>1</sup> IS ACETYLACETONE ISONICOTINOYLHYDRAZONE) WITH LARGE INTRA- AND INTERMOLECULAR CHANNELS

The solvated complex [МоО2(L1)]4dimethylformamide (I) was synthesized. Its structure wasdetermined by X-ray diffraction analysis. The crystal structure is composed of the tetranuclear complexes [МоО2(L1)]4 (Ia) as the structural units lying on crystallographic twofold axes. Both crystallographically independent molybdenum atoms are in a distorted octahedral coordination environment formed by two cis-О(oxo) ligands, two N(L1) atoms of two molecules Ia in trans positions to the О(oxo) ligands, and two О(L1) atoms of one complex molecule in cis positions to О(oxo) and trans to each other. Each (L1)2– ligand is coordinated to two Мо atoms in a tetradentate tridentate-chelating (2О, N) bridging (N) mode. The average bond lengths in complex Iа are as follows: Мо–О(oxo), 1.701 Å; Мо–N(L1), 2.460 (b) and 2.214 Å (c); Мо–О(L1), 1.980 Å. The О(oxo)–МоО–(oxo) bond angle is 105.6°. The ordered dimethylformamide molecule is located in a narrow channel in the structure. The strongly disordered (non-located) solvent molecules (methanol/dimethylformamide/water) occupy wide channels in the structure of I.

Optical and Structural Properties of ESIPT Inspired HBT-Fluorene Molecular Aggregates and Liquid Crystals.

In bulk materials, positional isomers not only help in understanding how slight difference in molecular structure alters the crystal packing and optical properties, but also play a key role in developing new type of materials for functional applications. A detailed study on the photophysical properties of fluorene-HBT positional isomers in solution and in the solid state providing a molecular level understanding of the factors which influence fluorescence behavior is reported. Two molecules Ia and IIa were synthesized by Suzuki coupling reaction and their photophysical properties were compared to positional isomers Ib and IIb. Crystal structure analyses and density functional theory (DFT) computation studies were performed to understand structure-properties relation and the results reveal that changing substitution pattern has a marked influence on their packing modes and luminescence properties. Strong noncovalent interactions (π-π) in the solid state hamper the excited state intramolecular proton transfer (ESIPT) process which causes fluorescence quenching in the solid state (Ia and IIa = Φf, 28-40%; Ib and IIb = Φf, 55-67%). Compounds show solvent-responsive and aggregation induced emission (AIE) properties. Bent structures of Ia with double and symmetric substitution of ESIPT motifs exhibit particularly unique condensed phase upon heating, confirmed as a nematic liquid crystalline phase, and this is the first report on the ESIPT and AIE active liquid crystalline materials with a banana-shaped molecule.

Isomer effect on the near-infrared electrochromism of anthraquinone imides

To deeply explore the interplay between molecular structure and near-infrared electrochromism of anthraquinone imides, two pairs of unsubstituted isomers (Ia and Ib) and nitro-substituted isomers (IIa and IIb) of anthraquinone imides were synthesized, in which the molecules Ia and IIa took more linear shapes than Ib and IIb. Cyclic voltammetry and spectroelectrochemistry were combined to investigate their electrochemical properties. Cyclic voltammetry showed that Ib and IIb revealed decreased first reduction potentials and low cyclic stability compared to their isomers, indicating that the isomerization weakened the stabilization effect. Upon one-electron reduction, both the absorption wavelengths and absorption intensities of radical anions were greatly dependent on the structures of isomers. The radical anions of Ia, IIa, and IIb illustrated NIR absorptions peaked at 820, 1260, and 1380nm, respectively, but that of Ib exhibited only weak absorption in the visible region centered at 660nm. Gaussian calculations suggested that the electrons were delocalized over the whole molecular skeletons of Ia and IIa radical anions, but the effective conjugation length was interrupted on the imide section in both Ib and IIb. The isomer effects on the effective conjugation length and electron density distribution were considered to rationalize the different electrochromic behaviors.

Synthesis and structure of tetraphenylantimony and triphenylantimony 4-oxybenzoates

Solvate Ph3Sb[OC(O)C6H4(OH-4)]2 · 1/2Et2O (I) has been synthesized by the reaction between triphenylantimony and 4-oxybenzoic acid in the presence of hydrogen peroxide in diethyl ether. Tetraphenylantimony 4-oxybenzoate, which crystallizes from DMSO in the form of solvate Ph4SbOC(O)C6H4(OH-4) · DMSO (II), has been synthesized from pentaphenylantimony and triphenylantimony bis(4-oxybenzoate) or 4-oxybenzoic acid. According to X-ray diffraction data, an antimony atom in molecules of compounds I and II has a trigonal bipyramidal coordination. Crystals of compound I contain two crystallographically independent types of molecules (A and B). The Sb-C and Sb-O distances, the equatorial CSbC and axial OSbO angles are, respectively, 2.083(9)–2.103(8)A; 2.068(5), 2.128(5)A; 117.6(3)°–124.2(3)° and 171.5(2)° (IA); 2.103(9)–2.135(8)A; 2.086(5), 2.154(6)A;110.2(3)°–138.0(4)° and 174.8(2)° (IB). In compound II, Sb-C is 2.117(2)–2.175(2) A, Sb-O is 2.247(2) A, and CeqSbCeq and OSbCax angles are 110.89(9)°–133.30(9)° and 177.05(7)°, respectively. The Sb…O=C intramolecular contacts are 3.151(7), 3.153(8) A (IA), 2.985(8), 3.008(9) A (IB), and 2.975(5) A (II). Molecules IA and IB are conformation isomers, which differ from each other by the arrangement of carboxyl groups with respect to the equatorial plane.

Tri- and tetraphenylantimony propiolates: Syntheses and structures

The reaction of triphenylantimony with propiolic acid in the presence of hydrogen peroxide (molar ratios 1 : 2 : 1 and 1 : 1 : 1) in diethyl ether affords triphenylantimony dipropiolate Ph3Sb[OC(O)C≡CH]2 (I) and μ2-oxobis[(propiolato)triphenylantimony] [Ph3SbOC(O)C≡CH]2O (II). Tetraphenylantimony propiolate Ph4SbOC(O)C≡CH (III) is synthesized from pentaphenylantimony and propiolic or acetylenedicarboxylic acid in toluene. According to the X-ray diffraction data, the crystals of compounds I and III include two types of crystallographically independent molecules (a and b). The antimony atoms in molecules Ia, Ib, II, IIIa, and IIIb have the trigonal-bipyramidal coordination mode with different degrees of distortion. The OSbO and OSbC axial angles are 176.8(2)° (Ia, Ib), 170.17(15)°, 178.78(14)° (II), and 173.2(5)°, 174.4(5)° (IIIa, IIIb). The CSbC equatorial angles lie in the ranges 108.2(3)°–143.1(3)° (I), 109.0(2)°–131.0(2)° (II), and 113.1(4)°–125.4(4)° (III). The SbOSb angle in II is 141.55(19)°. The Sb-C bond lengths are 2.103(8)–2.141(5) (I), 2.105(5)–2.119(5) (II), and 2.076(12)–2.166(13) A (III). The Sb-O distances increase in a series of I, II, and III: 2.139(6)–2.156(7) (Ia, Ib); 2.206(4), 2.218(3) (II); and 2.338(10), 2.340(10) A (III).

2-(diphenylphosphinylmethoxy)aniline: Synthesis, vibrational spectra, and crystal structure

The synthesis, vibrational spectra, and X-ray diffraction analysis results for 2-(diphenylphosphinylmethoxy) aniline, 2-[(C6H5)2P(O)OCH2]C6H4NH2(I), are described. The crystals are monoclinic: a = 18.4515(17) A, b = 10.5421(12) A, c = 17.897(2) A, β = 104.479(8)°, V = 3370.7(6) A3, Z = 8, space group P21/c, R = 0.0546 for 1770 reflections with I > 2σ(I). The unit cell contains two crystallographically independent molecules Ia and Ib joined by an N-H …O hydrogen bond between a hydrogen atom of the amino group of aniline in molecule Ia (Ib) and the phosphoryl oxygen atom of molecule Ib (Ia) (O…H 2.18 and 2.19 A, N…O, 2.979(5) and 3.000(5) A; NHO angle, 154° and 157°).

Molecular and crystal structures of decamethylruthenocene (η5-C5 Me 5)2Ru in the temperature range 153–300 K: Thermal motion in a crystal according to X-ray diffraction data

The crystal structure of decamethylruthenocene (η5-C5Me5)2Ru (I) is investigated by X-ray diffraction. It is demonstrated that the compound studied crystallizes in two polymorphic modifications, namely, modification Ia with space group P21/m (Z = 2) in the temperature range 153–300 K and modification Ibwith space group P21/n (Z = 4) at 203 K. No temperature phase transition between the modifications is found. In crystal Ia, the molecule occupies a special position in the mirror plane. In crystal Ib, the molecule is located in the general position. The cyclic ligands η5-C5Me5, (Cp*) are aligned parallel to each other and adopt an eclipsed conformation. The bond lengths in compounds Ia and Ib are identical. Analysis of the anisotropic displacement parameters of the atoms indicates that molecules Ia and Ib are not structurally rigid and that the Cp* rings involved in these molecules can execute independent librations. In the temperature range 153–300 K, the Cp*(1) ligand in molecule Ia is statically disordered over two positions. The barrier heights B5 for rotation of the Cp* ligands are estimated both from the root-mean-square amplitudes of librations 〈ϕ2〉 and with the use of the atom-atom potential method.

Crystal and molecular structure of the ethanol solvate of 2-[bis(diphenylphosphoryl)methyl]phenol

Crystal and molecular structure of the ethanol solvate of 2-[bis(diphenylphosphoryl)methyl]phenol, C31H26O3P2·3/4 C2H5OH (I), was determined by X-ray diffraction analysis. Crystals I are monoclinic: a=11.896(3), b=17.207(3), c=28.421(6) A, β=90.75(2)°, Z=8, space group P21/c. The structure of I was solved by direct methods and refined anisotropically by large-block least-squares analysis to R=0.066 (CAD-4 automatic diffractometer, λMoKα radiation, 3650 independent reflections with I≥3σ). The crystal structure of I contains two independent molecules, Ia and Ib, of the basic substance and two independent solvate molecules of ethanol. The P atoms in molecules Ia and Ib have distorted tetrahedral environments; the average bond lengths are: P=O 1.476(3), P-C(sp3)=1.833(4) and P-C(Ar)=1.809(4) A. Molecule Ia has an approximate symmetry plane Cs. The conformation of molecule Ib differs from that of Ia in rotation of one diphenylphosphoryl substituent around the P-C(sp3) bond by an angle of ≈34°. In molecule Ia, the O=P-C-P=O fragment has the form of a chela with two nearly parallel P=O bonds. In the crystal structure of I there are O-H...O=P intermolecular H-bonds; in molecules Ia and Ib there is an intramolecular H-bond of C-H...OH type.

Class II antigens of the major histocompatibility complex are increased in lungs of bleomycin-treated rats

The expression of class II molecules (Ia) of the major histocompatibility complex by isolated alveolar macrophages (AM) and alveolar type II cells from the lungs of rats with bleomycin-induced pulmonary fibrosis was examined. The percentage of Ia-positive AM and type II cells from rats treated with bleomycin as detected by flow cytometry was increased three times and two times, respectively, over the values obtained from control rats. The relative density of Ia expression, determined with a radioimmunoassay technique, showed a 50% increase in Ia density on AM and a 35% increase on type II cells. Recombinant interferon-gamma increased the expression of Ia on type II cells in vitro by 35% to the level obtained on type II cells in bleomycin-induced lung disease. We conclude that the increase of Ia expression on cells of the immune system and on pulmonary epithelial cells may have an important role in the initiation and/or amplification of inflammatory reactions in the lung and may contribute to the development of pulmonary fibrosis.

Synthesis and crystal structure of 6-amino-2-(p-aminophenyl)-4-phenylquinazoline

6-Amino-2-(p-aminophenyl)-4-phenylquinazoline (I), a monomer for the preparation of polymers, has been synthesized and studied by x-ray diffraction. The basic geometric characteristics of the molecule of compound (I) have been established-the small angle between the vectors along the C-NH2 bonds [3.0 and 5.7° in the two symmetrically independent molecules (Ia) and (Ib), with distance between the N atoms of the amino groups 11.908 and 11.767(3) A] and the coplanarity of the p-aminophenyl ring and the quinazoline rings (dihedral angle 1.0 and 3.3°)- and together with available data indicate the possibility of obtaining rigid-chain polymers based on compound (I).

Effects of Iodide on Class II-MHC Antigen Expression in Iodine Deficient Hyperplastic Thyroid Glands

The expression of major histocompatibility complex class II molecules (Ia antigen) has been analyzed by immunoperoxidase staining in thyroids of normal C3H mice, of iodine-deficient mice with a hyperplastic goiter and of mice during goiter involution induced by administration of either a high iodide dose (HID, 10 micrograms/day) for 0.5 to 8 days or a moderate iodide dose (MID, 1 microgram/day) or triiodothyronine (T3, 1 micrograms/day) for 2 days. In normal and in hyperplastic thyroids, few interstitial cells were Ia positive (monoclonal antibodies, mAb, M5/114, ER-TR3). Their number was unchanged when goiter involution was induced by MID or by T3, but was significantly increased (p less than 0.05) after HID. It was maximal at days 1 and 2 of involution, decreased thereafter but remained higher (p less than 0.05) than in controls after 8 days. The Ia positive cells were mainly macrophages and, to a lesser extent, dendritic cells. Macrophages were identified by their heterogeneous content and their numerous lysosomes. They were stained with anti-Mac-1 (M1/70) and anti-Mac-2 (M3/38) mAb. Dendritic cells were characterized by their slender cytoplasmic processes, indented nucleus and pale cytoplasm. They were positive for NLDC-145 and MIDC-8 mAb whose specificity for dendritic cells has been demonstrated in lymphoid organs. During the whole period of involution analyzed, Ia antigens were not expressed on follicular cells. Since macrophages and dendritic cells are known to be involved in the pathogenesis of immune disorders, the inflammation induced by administration of HID to iodine-deficient mice could be considered as the early step of an immunological reaction.

X-ray study of the hetero ring flexibility in trans-5,6- trimethylene- and tetramethylene-5,6-dihydro 2-phenyl-[4 H]-1,3-thiazines

The structures to two 1,3-thiazine derivatives differing only in the number of CH 2 groups in their trans fused hydrocarbon ring ( n  3 for I and n  4 for II) have been established by X-ray crystallography from diffractometer data. Crystals of I ( trans-5,6- trimethylene-5,6-dihydro-2-phenyl-[4 H] - 1,3-thiazine) are triclinic, space group P 1 with a = 7.661(1), b = 8.282(1), c = 9.566(2) Å, α = 91.75(1), β = 100.72(1), γ  105.45(1)° Z = 2, D c = 1.260 g cm -3. Crystals of II ( trans-5,6-tetramethylene-5,6-dihydro-2-phenyl [4 H]-1,3-thiazine) are monoclinic, space group P2 1/ c with a = 7.914(2), b = 19.362(13), c = 8.440(1) Å, β = 109.16(2)°C Z = 4, D c = 1.258 g cm -3. The structures determined by Patterson ( I) and direct ( II) methods were refined to R = 0.050 for 1330 reflections of I and R = 0.082 for 1012 reflections of II. The proper treatment of the positional disorder of the carbon atoms (C(5) and C(6)) forming the trans ring junction in I discovered two discrete conformations with a ratio of 1:2. The opposite chirality of atoms C(51) and C(52), and C(61) and C(62), indicates a simultaneous configurational disorder with a pattern of total disorder: AB̄B̄AB̄B̄. The puckering parameters of the hetero rings in the same enantiomers of molecules IA, IB and II indicate a connection between the conformers: 5 E( II)→ 5 H 6( IB)→ E 6 IA) via pseudorotation. Their relationship is discussed and compared with the conformational freedom of the analogous 1,3-oxazine derivatives.

T cell activation: differences in the signals required for IL 2 production by nonactivated and activated T cells.

Soluble antibodies against the T3/antigen receptor complex alone are not sufficient to induce proliferation and interleukin 2 expression by T lymphocytes. An additional requirement is the presence of accessory cells (AC). In this model, AC provide at least two functions required for T cell activation: 1) the surface interaction of T3 antibodies with Fc receptors on the AC surface and 2) the production of soluble mediators such as interleukin 1 (IL 1). In the experiments reported here, these stimuli are represented by T3 antibodies immobilized onto Sepharose beads and by recombinant IL 1. In this study we investigated differences in activation requirements in resting and activated T cells. Resting T cells were represented by AC-depleted peripheral blood mononuclear cells (PBMC) or the T cell line Jurkat, which phenotypically resembles a resting T cell. Activated T cells were represented by T cell clones and the T cell line HUT 78, which express the activation molecules Ia and the IL 2 receptor (Tac). In resting cells, activation required the presence of three different signals: perturbation of the T3/antigen receptor complex by T3 antibodies, surface redistribution of T3/antigen receptor complexes, and presence of IL 1. In contrast, activated T cells require only perturbation and redistribution of T3/antigen receptor complexes and not IL 1 for the induction of proliferation or IL 2 production. Possible mechanisms of intracellular signaling for these stimuli are discussed.

Guinea pig lymphocyte antigen molecules Ia.3,5 and Ia.8 share structural homology expected for alleles.

Because of the lack of I region recombinant guinea pig strains, rigorous comparative chemical analyses of guinea pig Ia alloantigens have been utilized to gather structural information that would allow tentative assignment of I region alleles. In this study, the B/Lac Ia.8 molecule was chemically compared to the strain 13 Ia.3,5 molecule and the strain 2 Ia.2 and Ia.4,5 molecules. SDS-PAGE, IEF, and Cleveland peptide mapping demonstrated a significant degree of homology between the Ia.8 and Ia.3,5 alpha-chains. HPLC mapping of trypsin/chymotrypsin cleavage products revealed an overall coincidence of peptides of 57 and 68% for the comparisons of the Ia.8 and Ia.3,5 alpha- and beta-chains respectively. In contrast, comparisons of Ia.8 and Ia.2 alpha- and beta-chains exhibited a significantly lower degree of similarity--39 and 47% respectively. The degree of homology seen in the Ia.8 and Ia.3,5 comparisons is consistent with those values seen in comparisons between the Ia.3,5 and Ia.4,5 molecules (putative allelic products of the guinea pig I region) and with those values obtained for allelic products of the mouse H-2 system. The results of this investigation strongly suggest that the Ia.8, Ia.3,5, and Ia.4,5 molecules are the products of alleles at the Ia alpha- and beta-chain loci.