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71.
Guney E Kaya Y Yilmaz VT Gumus S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1171-1178
New palladium(II) and platinum(II) complexes of saccharinate (sac) with 2-(2-pyridyl)benzimidazole (pybim) have been synthesized and characterized by elemental analysis and spectroscopic techniques. From the experimental studies, these complexes were formulated as [Pd(pybim)(sac)2] (1), and [Pt(pybim)(sac)2]·4H2O (2). The ground-state geometries of both complexes were optimized using density functional theory (DFT) methods at the B3LYP level. A bidentate pybim ligand together with two N-coordinated sac ligands form the square-planar MN4 coordination geometry around the palladium(II) and platinum(II) ions. The calculated IR and UV-vis spectral data have been correlated to the experimental results. Thermal analysis data support the molecular structures of both complexes. 相似文献
72.
Hayriye Ozer Şafak Ozhan Kocakaya Abuzer Akgun Halil Hoşgören Mahmut Togrul 《Tetrahedron: Asymmetry》2009,20(13):1541-1546
Pyridine-based macrocycles were prepared by treating 2,6-bis[[2′6′-bis(bromomethyl)-4′-methylphenoxy]methyl]pyridine 3 with the appropriate chiral aminoalcohols. The enantiomeric recognition of these macrocycles bearing aminoalcohol subunits of the pyridinocrown type ligand was evaluated for chiral organic ammonium salts by UV titration. The important differences were observed in the Ka values of (R)-Am2 and (S)-Am2 for (S,S,S)-1, (S,S,S)-2 and (S,S,S)-3 hosts, KS/KR = 5.0, KS/KR = 2.4 and KS/KR = 5.0, respectively. There seems to be a general tendency for hosts to recognise (S)-enantiomers for both Am1 and Am2. 相似文献
73.
Intrinsic tryptophan (Trp) fluorescence is often used to determine conformational changes of proteins. The fluorescence of multi-Trp proteins is generally assumed to be additive. This assumption usually holds well if Trp residues are situated at long distances from each other in the absence of any excited state reactions involving these residues and therefore when energy transfer does not occur. Here, we experimentally demonstrate energy transfer among Trp residues and support it by a Master Equation kinetic model applied to a therapeutic monoclonal antibody (mAb). The mAbs are one of the most studied and important biologics for the pharmaceutical industry, and they contain many Trp residues in close proximity. Understanding mAb fluorescence is critical for interpreting fluorescence data and protein-structure relationships. We propose that Trp residues could be categorized into three types of emitters in the mAbs. Experimentally, we categorize them according to solvent accessibility based on dependence of their fluorescence lifetime on the external quencher concentration and their emission wavelength. Theoretically, we categorize with molecular dynamics simulations according to their solvent accessibility. This method of combinatorial mapping of fluorescence characteristics can be utilized to illuminate structural aspects as well as make comparisons of drug formulations for these pharmaceutical proteins. 相似文献
74.
Ren Zhang Gurpreet Singh Alei Dang Lu Dai Michael R. Bockstaller Bulent Akgun Sushil Satija Alamgir Karim 《Macromolecular rapid communications》2013,34(20):1642-1647
Sharp dynamic thermal gradient (∇T ≈ 45 °C mm−1) field‐driven assembly of cylinder‐forming block copolymer (c‐BCP) films filled with PS‐coated gold nanoparticles (AuNPs; dNP ≈ 3.6 nm, φNP ≈ 0–0.1) is studied. The influence of increasing AuNP loading fraction on dispersion and assembly of AuNPs within c‐BCP (PS‐PMMA) films is investigated via both static and dynamic thermal gradient fields. With φNP increasing, a sharp transition from vertical to random in‐plane horizontal cylinder orientation is observed due to enrichment of AuNPs at the substrate side and favorable interaction of PMMA chains with gold cores. Furthermore, a detachable capping elastomer layer can self‐align these random oriented PMMA microdomains into unidirectional hybrid AuNP/c‐BCP nanolines, quantified with an alignment order parameter, S.
75.
The reaction of silver nitrate with sodium saccharinate (Na[sac]) in the presence of 2-pyridinepropanol in aqueous solution yields the title complex, Na[Ag(sac)2]. The compound crystallizes in the triclinic space group [a = 8.0481(6), b = 9.0587(6), c = 11.1642(8) Å; α = 100.064(3), β = 99.917(3) and γ = 92.367(3)°, Z = 2]. The structure consists of Na+ and [Ag(sac)2]- ions, in which each silver(I) ion is doubly bridged by the sac ligands, exhibiting a distorted 'T' shaped AgN2O coordination arrangement with one long [Ag-Osulfonyl = 2.6390(10) Å] and two shorter bonds [Ag-N = 2.1405(11) and 2.1570(11) Å]. The coordination around silver(I) is trigonal planar and the N-Ag-N bond angle is 158.99(5)°. The Na+ ion is five-coordinate with two carbonyl and three sulfonyl O atoms of the adjacent sac ligands and acts as a bridge between [Ag(sac)2]- units, resulting in a three-dimensional network. The i.r. spectra and thermal decomposition behaviour of Na[Ag(sac)2] are discussed in detail. 相似文献
76.
The complex [Pb(H2O)(μ‐OAc)(μ‐sac)]n with acetate (OAc) and saccharinate (sac) ligands was characterized by IR, elemental analysis and X‐ray crystallography. The mixed‐anion lead(II) complex crystallizes in the triclinic crystal system with the space group of P1¯. The single crystal X‐ray analysis shows that the complex is a coordination polymer in which the lead(II) ions have a highly distorted pentagonal bipyramidal coordination geometry. Lead(II) ions are bridged by carboxylate groups in a zigzag arrangement forming one‐dimensional infinite chains, which are also linked by sac bridges and aromatic π‐π contacts between the adjacent phenyl rings of sac ligands, resulting in a three‐dimensional network. One water molecule coordinates the lead(II) ion and also forms weak hydrogen bonds with the sulfonyl oxygen atoms of the neighboring sac ligands. The sac ligand acts as a bridging ligand through the nitrogen and carbonyl oxygen atoms, while the carboxylate moiety of the acetate ligand shows an unusual (bidentate, and bridging) coordination behaviour, which was observed for the first time in the structure. 相似文献
77.
Two trans saccharinate (sac) complexes of cadmium(II) with 2‐pyridylethanol (pyet) were synthesized and characterized by elemental analyses, FT—IR spectroscopy, thermal analysis and single crystal X‐ray diffractometry. The [Cd(sac)2(pyet)2] ( 1 ) and [Cd(sac)2(H2O)(dmso)(pyet)] ( 2 ) complexes crystallize in the monoclinic (P21/c) and orthorhombic [P212121] crystal systems, respectively. The sac ligands in both complexes are N‐coordinated and located in trans positions, while the pyet molecules act as a bidentate N‐ and O‐donor ligand forming two six‐membered chelate rings. Thermal decomposition of the complexes in air results in elimination of aqua, dmso and pyet ligands, respectively, forming cadmium saccharinate as a stable intermediate, which also decomposes at higher temperatures to give cadmium oxide. 相似文献
78.
Two bis(saccharinato) (sac) complexes of mercury(II) with 2–aminomethylpyridine (ampy) and 2–aminoethylpyridine (aepy) were synthesized and characterized by means of elemental analysis, FT–IR spectroscopy and thermal analysis and single crystal X–ray diffraction. trans–[Hg(sac)2(ampy)2] ( 1 ) crystallizes in the monoclinic space group P21/c [a = 10.8274(4), b = 16.4903(6), c = 7.7889(3) Å; β = 99.500(1)°] and [Hg(sac)2(aepy)] ( 2 ) also crystallizes monoclinic in space group P21/n [a = 9.0423(4), b = 14.0594(6), c = 18.0146(8) Å; ß = 98.806(1)°]. Both 1 and 2 consist of neutral monomeric units. The mercury(II) ion in 1 lies on an inversion centre and exhibit distorted octahedral coordination by two sac anions and two ampy ligands, whereas the mercury(II) ion in 2 is tetrahedrally coordinated by an aepy and two sac ligands. The sac ligands in both complexes are N–coordinated, while the ampy and aepy ligands act as a bidentate ligand forming two symmetrically chelate rings around the mercury(II) ion. 相似文献
79.
Selcuk Demir Veysel T. Yilmaz Omer Andac William T. A. Harrison 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o407-o408
The title compound, C4H14N2O2+·HPO42?·H2O, contains alternating interleaved layers of hydrogenphosphate and N‐(2‐hydroxyethyl)ethylenediammonium moieties. The water molecules are associated with channel‐like voids in the structure and a network of hydrogen bonds stabilizes the crystal packing. 相似文献
80.
Omer Andac Yildiray Topcu Veysel T. Yilmaz William T. A. Harrison 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):m14-m16
The structure of the title complex consists of isolated [Cd(C7H4NO3S)2(C4H11NO2)2] units. The Cd2+ cation lies on an inversion centre and is octahedrally coordinated by two N,O‐bidentate diethanolamine (dea) and two N‐bonded saccharinate (sac) ligands [saccharin is 1,2‐benzisothiazol‐3(2H)‐one 1,1‐dioxide]. The dea ligands constitute the equatorial plane of the octahedron, forming two five‐membered chelate rings around the CdII ion, while the sac ligands are localized at the axial positions. The Cd—Nsac, Cd—Ndea and Cd—Odea bond distances are 2.3879 (12), 2.3544 (14) and 2.3702 (13) Å, respectively. The H atoms of the free and coordinated hydroxyl groups of the dea ligands are involved in hydrogen bonding with the carbonyl and sulfonyl O atoms of the neighbouring sac ions, while the amine H atom forms a hydrogen bond with the free hydroxyl O atom. The individual molecules are held together by strong hydrogen bonds, forming an infinite three‐dimensional network. 相似文献