@article { ISI:000316451500010, title = {Easy and multigram-scale synthesis of pillar[5]quinone by the hypervalent iodine oxidation of 1,4-dimethoxypillar[5]arene}, journal = {Synthesis-Stuttgart}, volume = {45}, number = {7}, year = {2013}, month = {APR}, pages = {896-898}, publisher = {GEORG THIEME VERLAG KG}, address = {RUDIGERSTR 14, D-70469 STUTTGART, GERMANY}, abstract = {

Pillar[5]quinone (P[5]Q), a potential molecule for anion recognition and supramolecular host-guest chemistry, has not as yet been used for practical purposes, presumably due to the synthetic difficulties in obtaining it in large amounts. Herein, we reveal an easy-to-operate and chromatography-free synthetic strategy that can furnish P[5]Q on a multigram scale; its success relies on the utility of hypervalent iodine, generated in situ from Oxone/ iodobenzene, as an efficient oxidant. Pillar[5]quinone was obtained in multigram quantities by oxidation of 1,4-dimethoxypillar[5]arene with Oxone/iodobenzene and simple purification by crystallization from 1,1,2,2-tetrachloroethane, thus opening up the opportunity to explore the properties of this interesting macrocyclic quinone.

}, keywords = {hypervalent iodine oxidation, macromolecules, pillar-arenes, supramolecular chemistry}, issn = {0039-7881}, doi = {10.1055/s-0032-1318390}, author = {Shivakumar, Kilingaru I. and Sanjayan, Gangadhar J.} } @article { ISI:000352246100007, title = {Exploiting powder x-ray diffraction to establish the solvent-assisted solid-state supramolecular assembly of pillar[5]quinone}, journal = {Crystal Growth \& Design}, volume = {15}, number = {4}, year = {2015}, month = {APR}, pages = {1583-1587}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

We report the solvent-mediated supramolecular assembly of pillar[5]quinone (P[5]Q), a symmetric cyclamer containing five benzoquinone moieties bridged by five alternating methylene units. The supramolecular assembly of P[5]Q is shown to be facilitated by 1,1,2,2-tetrachloroethane (TCE) as solvent, producing a microcrystalline solvate material P[5]Q(.)2TCE with a fluffy texture. Optical and electron microscopy reveal that this material has a rod-shaped morphology, extending to several micrometers in length. Due to the microcrystalline nature of the material, structure determination was carried out directly from powder X-ray diffraction data, augmented by high-resolution solid-state C-13 NMR. The two crystallographically distinct TCE molecules occupy different types of void in the structure and have different dynamic properties. Crystallization of P[5]Q was attempted from a large number of different solvents, but only TCE was found to facilitate the formation of a crystalline phase. Indeed, features of the crystal structure suggest that the TCE component plays an important role in promoting the columnar assembly of P[5]Q molecules.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.5b00277}, author = {Shivakumar, Kilingaru I. and Yan, Yuncheng and Hughes, Colan E. and Apperley, David C. and Harris, Kenneth D. M. and Sanjayan, Gangadhar J.} } @article {43878, title = {Mixed-stack charge transfer crystals of pillar[5]quinone and tetrathiafulvalene exhibiting ferroelectric features}, journal = {Chemistry- A European Journal }, volume = {23}, year = {2017}, month = {SEP}, chapter = {12630-12635}, abstract = {

Ferroelectric materials find extensive applications in the fabrication of compact memory devices and ultra-sensitive multifunctional detectors. Face-to-face alternate stacking of electron donors and acceptors effectuate long-range unidirectional ordering of charge-transfer (CT) dipoles, promising tunable ferroelectricity. Herein we report a new TTF-quinone system-an emerald green CT complex consisting pillar[5]quinone (P5Q) and tetrathiafulvalene (TTF). The CT crystals, as determined by single crystal synchrotron X-ray diffraction, adopt a 1:1 mixed-stack arrangement of donor and acceptor with alternating dimers of TTF and 1,4-dioxane encapsulated P5Q. The TTF-P5Q.dioxane crystal possesses a macroscopic polarization axis giving rise to ferroelectricity at room temperature. The CT complex manifests ferroelectric features such as optical polarization rotation, temperature-dependent phase transition and piezoelectric response in single crystals. Ferroelectric behavior observed in P5Q-based CT complex widens the scope for further work on this structurally intriguing and readily accessible cyclic pentaquinone.

}, keywords = {Acceptor, Charge-transfer complexes, Chemistry, Conductors, DDQ, Donor, ferroelectric, Macrocycles, Organic Metals, Pi-interaction, Pillar[5]quinone, salts, Transfer Complexes, Transport}, issn = {0947-6539}, doi = {10.1002/chem.201702577}, author = {Shivakumar, Kilingaru I. and Swathi, Kadaba and Goudappagouda and Das, Tamal C. and Kumar, Ashwani and Makde, Ravindra D. and Vanka, Kumar and Narayan, Kavassery S. and Babu, Sukumaran Santhosh and Sanjayan, Gangadhar J.} } @article {46088, title = {Conducting nanofibres of solvatofluorochromic cyclohexanetrione-dithiolylidene-based C-3 symmetric molecule (vol 54, pg 212, 2018)}, journal = {Chemical Communications}, volume = {55}, year = {2019}, month = {JUN }, pages = {6461}, type = {Correction}, abstract = {

Correction for {\textquoteleft}Conducting nanofibres of solvatofluorochromic cyclohexanetrione-dithiolylidene-based C-3 symmetric molecule{\textquoteright} by Kilingaru I. Shivakumar et al., Chem. Commun., 2018, 54, 212-215.

}, issn = {1359-7345}, doi = {10.1039/c9cc90229e}, author = {Shivakumar, Kilingaru I. and Goudappagouda and Gonnade, Rajesh G. and Babu, Sukumaran Santhosh and Sanjayan, Gangadhar J.} }