Saturday, 06 March 2021

Research

Ongoing research activities and interests:
  • Conventional disk-like and rod-shaped mesogens derived from new rigid cores
  • Supramolecular liquid crystals involving inter- and/or intramolecular H-bonding
  • Organic (covalent & ionic) and metal-containing banana-shaped mesogens
  • Mesoionic and heterocyclic liquid crystals (LCs)
  • Chiral low molar mass oligomeric LCs (dimers, trimers, tetramers and pentamers)
  • Low molar mass luminescent LC derived from fluorophores
  • Mesogens showing technologically important LC phases at room temperature
  • Supramolecular (H-bonded) conventional and non-conventional LCs
  • Photoresponsive and photochromic low- and  high molar mass materials for doping
  • Functional liquid crystalline ligands for capping of certain nanopaticles
  • Organic-gels derived from mesogens; liquid-crystalline physical gels
  • Porous materials

Liquid crystals (LCs) represent a fascinating class of soft condensed matter where the subtle balance between order and fluidity of the molecules exist. They show a range of exceptional properties that are not only fascinating from basic science point of view, but also hold tremendous potential for various innovative applications. Thus, continued and expanded efforts are in progress to realize self-assembling organic motifs, exhibiting a range of functional features with a common factor of all being LC behavior. The research work has focused, and continues to center on the design, synthesis and characterization of three broad types of LCs.

(i) Conventional LCs: Novel discotics such as tris(N-salicylideneaniline)s, spin-carrying tripehnylenes and luminescent s-triazines have been accomplished and figured out their possible utility in applied science. Polar rod-like LCs with dipole moment (m = 5-6D), derived from mesoionic ring, have been prepared and their potential use in displays has been exposed.

 Selected pulications on Discotics:

  • J. Am.Chem.Soc. 2004, 126, 650            
  • Tetrahedron Lett. 2006, 47, 7071
  • J. Org. Chem., 2007, 72,8308
  • J. Mater. Chem., 2007, 17, 4521.
  • J. Mater. Chem., 2008, 18, 3433
  • J. Org. Chem., 2009, 74, 3168
  • Tetrahedron Lett. 2012, 53, 186
  • Tetrahedron Lett., 2010, 51, 4579
  • Tetrahedron Lett. 2012, 53, 7108
  • Tetrahedron Lett. 2010, 51, 4579
  • Tetrahedron Lett. 2012, 53, 186
  • J. Org. Chem. 2013, 78, 527
  • Adv. Optical Mater. 2015, 3, 1116

Selected pulications on Calamitics:

  • Tetrahedron Lett., 2005, 46, 6701-67
  • Chem. Comm. 2005, 1552
  • Tetrahedron Lett., 2005, 46, 2623
  • New J. Chem., 2015, 39, 2011
  • J. Phy. Chem. B. 2015,  119, 4539
  • J. Phy. Chem. B, 2015, 119, 11935
(ii) Non-Conventional LCs: A variety of oligomers comprising more than one mesogens linked via flexible spacer/s have been prepared; their LC properties are shown to be rewarding in many directions. A wide variety of banana-shaped LCs have been realized and their astonishing LC properties have been evidenced.

Selected pulications on LC OLigomers:

  • Chem. Commun., 2000, 57.
  • Phys. Rev. Lett., 2001, 87, 085504-1.
  • J. Mater. Chem., 2002, 12, 2225
  • Angew. Chem. Int. Ed., 2004, 43, 3429
  • Tetrahedron Lett., 2005, 46, 6701
  • Chem. Mater,   2006, 18, 1076
  • J. Mater. Chem., 2006, 16, 4099.
  • Chem. Mater, 2006, 18, 6100.
  • Chem. Mater, 2007, 19, 2463
  • Org. Lett. 2007, 9, 2641
  • Chem. Mater., 2007, 19, 6561
  • Tetrahedron, 2008, 64, 3760.
  • J. Mater. Chem., 2008, 18, 2096
  • J. Mater. Chem., 2008, 18, 2927
  • J. Mater. Chem., 2008, 18, 3433
  • J. Mater. Chem., 2009, 19, 2906
  • Tetrahedron, 2009, 65, 6403
  • J. Mater. Chem., 2011, 21, 4064
  • J. Phy. Chem. B, 2011, 115, 10849
  • New J. Chem., 2012, 36, 918
  • J. Phy. Chem. B, 2012, 116, 9549
  • New J. Chem., 2014, 38, 4235

Selected pulications on Banana-shaped LCs:

  • J. Mater. Chem., 2001, 11, 1818
  • Liq. Cryst., 2002, 29, 1181
  • Liq. Cryst., 2004, 31, 1027
  • Soft Matter, 2006, 2, 785
  • J. Chem. Res., 2006, 612
  • J. Mater. Chem., 2007, 17, 284
  • Beilstein J. Org. Chem., 2012, 8, 129

(iii) Supramolecular LCs: An elegant way of achieving LC dipeptides has been devised recently; their self-assembly, into H-bonded, oblique helical columnar phase, showing ferroelectric behavior with high spontaneous polarization (over 500 nC cm-2) value, has been established. Besides, all these supramolecules form stable gels in ethanol.

  •  Chem. Euro. J. 2008, 14, 10462
  • J. Phy. Chem. B, 2009 113, 6647
  • J. Phy. Chem. B, 2010, 114, 697
  • J. Appl. Phys., 2011, 109, 083537
  • RSC Advances, 2012, 2, 1592
  • NPG Asia Materials, 2012, 4, e11-1-7
  • Tetrahedron, 2012, 68, 6361
  • Liq. Cryst., 2014, 41, 1008

Sponsored Research Projects (as a PI):  Completed/On-going

  1. Project Title: Molecular Design, Synthesis and Characterization of Cholesterol-based Liquid Crystalline Dimers
    Project Status  : Completed - January 1, 2002 to December 31, 2004 (3 years)
    Funding Agency: CSIR: No. 01(1727) / 02/ EMR-II
    Co-investigators:Dr. D. S. Shankar Rao (CeNS)
     
  2. Project Title: Molecular Design to Stabilize Biaxial Nematic and Smectic Phases: Synthesis of Low Molar Mass Non-Conventional Liquid Crystals
    Project Status: Completed- March 1, 2005 to February 29, 2008 (3 years)
    Funding Agency: CSIR : No. 01(1931) / 04 / EMR-II  
    Co-investigators:Dr. S. Krishna Prasad and Dr. Geetha G. Nair (CeNS)
     
  3. Project Title: Synthesis and Liquid Crystal Behavior of Chiral Disc-Rod Oligomers
    Project Status: Completed - March  1, 2008 to February 28, 2011 (3 years)
    Funding Agency: CSIR : No. 01(2162) / 07 / EMR-II  
    Co-investigators: Dr. S. Krishna Prasad and Dr. D. S. Shankar Rao (CeNS)
     
  4. Project Title: Synthesis and Characterization of Tris(N-salicylideneaniline)s [TSAN] Based Disc-Shaped Liquid Crystals
    Project Status: Completed- January 22, 2008 to January 21, 2011 (3 years)
    Funding Agency: DST: No. SR / S1 / OC-06 /2007
    Co-investigators: Dr. S. Krishna Prasad and Dr. D. S. Shankar Rao (CeNS)
     
  5. Project Title:Synthesis and characterization of novel thermotropic liquid crystals: Functional discotics, dimers and dimer-like mesogens”  
    Project Status:In progress (Nearing successful completion) 
    Funding Agency: SERB, DST: No.SR/S1/OC-04/2012.

Sponsored Research Projects Being Obtained (as a Co-investigator) and Completed

  1. Project Title: Optically active dimesogenic bidentate ligands and their metal complexes: synthesis and evaluation of liquid crystal behavior”
    Project Status  :   Completed - April 01, 2008 to March  31, 2010 (2 years)
    Funding Agency: UGC F. No. MRP(S)-012/07-08/KABA031/UGC-SWRO
    Principal investigators: Dr. (Mrs.) Girija M. Sonar.