Structural characterization and molecular order of rodlike mesogens with three- and four-ring core by XRD and 13C NMR spectroscopy. 2013

M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
Department of Chemistry, S V University, Tirupati, India.

Structural characterizations using XRD and (13)C NMR spectroscopy of two rodlike mesogens consisting of (i) three phenyl ring core with a polar cyano terminal and (ii) four phenyl ring core with flexible dodecyl terminal chain are presented. The three-ring-core mesogen with cyano terminal exhibits enantiotropic smectic A phase while the four-ring mesogen reveals polymesomorphism and shows enantiotropic nematic, smectic C, and tilted hexatic phases. The molecular organization in the three-ring mesogen is found to be partial bilayer smectic Ad type, and the interdigitation of the molecules in the neighboring layers is attributed to the presence of the polar terminal group. For the four-ring mesogen, the XRD results confirm the existence of the smectic C and the tilted hexatic mesophases. A thermal variation of the layer spacing across the smectic C phase followed by a discrete jump at the transition to the tilted hexatic phase is also observed. The tilt angles have been estimated to be about 45° in the smectic C phase and about 40° in tilted hexatic phase. (13)C NMR results indicate that in the mesophase the molecules are aligned parallel to the magnetic field. From the (13)C-(1)H dipolar couplings determined from the 2D experiments, the overall order parameter for the three-ring mesogen in its smectic A phase has been estimated to be 0.72 while values ranging from 0.88 to 0.44 have been obtained for the four-ring mesogen as it passes from the tilted hexatic to the nematic phase. The orientations of the different rings of the core unit with respect to each other and also with respect to the long axis of the molecule have also been obtained.

UI MeSH Term Description Entries
D009570 Nitriles Organic compounds containing the -CN radical. The concept is distinguished from CYANIDES, which denotes inorganic salts of HYDROGEN CYANIDE. Nitrile
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D011789 Quantum Theory The theory that the radiation and absorption of energy take place in definite quantities called quanta (E) which vary in size and are defined by the equation E Quantum Theories,Theories, Quantum,Theory, Quantum
D002247 Carbon Isotopes Stable carbon atoms that have the same atomic number as the element carbon but differ in atomic weight. C-13 is a stable carbon isotope. Carbon Isotope,Isotope, Carbon,Isotopes, Carbon
D001713 Biphenyl Compounds Whitish aromatic crystalline organic compounds made up of two conjoined BENZENE rings. Compounds, Biphenyl
D014961 X-Ray Diffraction The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Xray Diffraction,Diffraction, X-Ray,Diffraction, Xray,Diffractions, X-Ray,Diffractions, Xray,X Ray Diffraction,X-Ray Diffractions,Xray Diffractions
D015394 Molecular Structure The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds. Structure, Molecular,Molecular Structures,Structures, Molecular
D050866 Liquid Crystals Materials in intermediate state between solid and liquid. Liquid Crystalline Materials,Mesomorphous Phase Materials,Crystal, Liquid,Crystals, Liquid,Liquid Crystal,Material, Mesomorphous Phase,Materials, Mesomorphous Phase,Mesomorphous Phase Material

Related Publications

M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
August 2015, Physical chemistry chemical physics : PCCP,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
October 2011, The journal of physical chemistry. B,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
November 2020, Magnetic resonance in chemistry : MRC,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
December 2015, The journal of physical chemistry. B,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
January 2011, The journal of physical chemistry. B,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
December 1980, Journal of pharmaceutical sciences,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
July 2021, Physical review. E,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
February 1994, The Journal of biological chemistry,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
March 2005, The journal of physical chemistry. A,
M Kesava Reddy, and K Subramanyam Reddy, and K Yoga, and M Prakash, and T Narasimhaswamy, and A B Mandal, and Nitin P Lobo, and K V Ramanathan, and D S Shankar Rao, and S Krishna Prasad
July 2019, The journal of physical chemistry. B,
Copied contents to your clipboard!