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91.
Rajkumar BJ Ramakrishnan V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(2):247-254
The two methionine cations in the asymmetric part of the unit cell of bis(DL-methionine dihydrogen phosphate) have different conformations. This, together with the different environments seen by the two -CH2- groups in each skeleton cause several of the group wavenumbers to occur as doublets or as broad bands. The anion contains two dissimilar P-O bonds, which distorts the phosphate tetrahedron. Due to this, the stretching wavenumbers appear as doublets. There is extensive hydrogen bonding in the system in all three crystallographic directions and this is responsible for the changes in the position and intensity of several bands. Fermi resonance has also been observed. 相似文献
92.
Sreedevi KC Thomas AP Ramakrishnan S Salini PS Holaday MG Reddy ML Srinivasan A 《Organic & biomolecular chemistry》2012,10(18):3600-3605
Synthesis, spectral and structural characterization of a pyrroloindolizine derivative having structural similarity with calix[2]pyrrole is described. Here, two pyrrole rings are connected with two meso-carbon atoms having an N,α-linkage and an α,β-linkage to afford the smallest analogue in the calixpyrrole family. Detailed NMR spectroscopic studies along with single crystal X-ray analysis confirm the assigned structure of the molecule. 相似文献
93.
We have postulated a novel pathway that could assist in the nucleation of soot particles through covalent dimerization and oligomerizations of a variety of PAHs. DFT calculations were performed with the objective of obtaining the relative thermal stabilities and formation probabilities of oligomeric species that exploit the facile dimerization that is known to occur in linear oligoacenes. We propose that the presence of small stretches of linear oligoacence (tetracene or longer) in extended PAH, either embedded or tethered, would be adequate for enabling the formation of such dimeric and oligomeric adducts; these could then serve as nuclei for the growth of soot particles. Our studies also reveal the importance of π‐stacking interactions between extended aromatic frameworks in governing the relative stabilities of the oligomeric species that are formed. © 2012 Wiley Periodicals, Inc. 相似文献
94.
L. Govindasamy D. Velmurugan V. Raghukumar Il‐Hawn Suh V. T. Ramakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):80-81
In the title compound, C29H30N6, the naphthyridine ring is almost planar with a dihedral angle of 5.4 (1)° between the pyridyl rings. The dihedral angles between the naphthyridine system and the diethylaminophenyl, phenyl and pyrrolidine rings are 53.1 (1), 19.8 (1) and 20.9 (1)°, respectively. The pyrrolidine ring adopts a half‐chair conformation. The molecule is stabilized by weak C—H?N interactions. 相似文献
95.
Kandasamy Chinnakali S. Shanmuga Sundara Raj Hoong‐Kun Fun Kamaraj Sriraghavan Vayalakkavoor T. Ramakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):227-228
In the title compound, C17H21NO3S, the S atom is in a distorted tetrahedral geometry and the N atom exhibits sp2 character. The antiperiplanar conformation is observed for the N and hydroxyl‐O atoms and the torsion angle around the N—C linkage is ?136.3 (2)°. The molecules are linked by O—H?O intermolecular hydrogen bonds to form an infinite one‐dimensional chains along the c axis. 相似文献
96.
Jin‐Baek Kim Ramakrishnan Ganesan So Young Yoo Jae‐Hak Choi Sang Yup Lee 《Macromolecular rapid communications》2006,27(17):1442-1445
Summary: A simple lithographic process in conjunction with a novel biocompatible nonchemically amplified photoresist material was successfully used for cell patterning. UV light irradiation on selected regions of the nonchemically amplified resist film renders the exposed regions hydrophilic by the formation of carboxylic groups. Mouse fibroblast cells were found to be preferentially aligned and proliferated on the UV light exposed regions of the nonchemically amplified resist film where carboxylic groups were present.
97.
A M Benial V Ramakrishnan R Murugesan 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(6):1199-1205
Infrared and laser Raman spectra of [Ni(II)(diars)2X]X, (X=Cl, Br and I) have been used as probes to determine the structures of chelated diarsine molecules. It has been observed that the effects of metal chelation and coordination geometry give rise to frequency shifts in these complexes. The variation in vibrational spectroscopic features indicates reduction in the symmetry of the complexes in the crystalline environment. The effect of halogen on the Ni-halogen stretching frequency of these square pyramidal complexes is not as significant as observed in the case of octahedral complexes. 相似文献
98.
A. Subbiah Pandi D. Velmurugan S. Shanmuga Sundara Raj Hoong‐Kun Fun V. Raghukumar V. T. Ramakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):723-725
In the title compounds, C17H15N3 and C20H22N4, the methyl derivative crystallizes with two molecules in the asymmetric unit, while the N,N‐diethylamino derivative crystallizes with one molecule per asymmetric unit. The biphenyl twist angle for both molecular structures is approximately 45°. The molecular packing is stabilized by N—H?N hydrogen bonds. 相似文献
99.
Palanisamy Shanmugasundaram Periyasamy Murugan Vayalakkavoor T. Ramakrishnan Narayanan Srividya Perumal Ramamurthy 《Heteroatom Chemistry》1996,7(1):17-22
Synthesis of 9-alkyl, 10-alkyl, 9,10-dialkyl, and 10-aryl-3,4,6,7,9,10-hexahydro-1,8(2H,5H)acridinedione (2a–r) are described as a new class of laser dyes. Reactions of diamines with methylene bis(cyclohexane-1,3-dione) yielded the respective bisacridinediones (3a–e). These dyes lase around 478–494 nm and are compared with the standard dye coumarin-102. © 1996 John Wiley & Sons, Inc. 相似文献
100.