Browsing by Author "Jha, P.K."

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Possible Room-Temperature Ferromagnetism in Self-Assembled Ensembles of Paramagnetic and Diamagnetic Molecular Semiconductors
(2016) Dhara, B.; Tarafder, K.; Jha, P.K.; Panja, S.N.; Nair, S.; Oppeneer, P.M.; Ballav, N.
Owing to long spin-relaxation time and chemically customizable physical properties, molecule-based semiconductor materials like metal-phthalocyanines offer promising alternatives to conventional dilute magnetic semiconductors/oxides (DMSs/DMOs) to achieve room-temperature (RT) ferromagnetism. However, air-stable molecule-based materials exhibiting both semiconductivity and magnetic-order at RT have so far remained elusive. We present here the concept of supramolecular arrangement to accomplish possibly RT ferromagnetism. Specifically, we observe a clear hysteresis-loop (Hc ? 120 Oe) at 300 K in the magnetization versus field (M-H) plot of the self-assembled ensembles of diamagnetic Zn-phthalocyanine having peripheral F atoms (ZnFPc; S = 0) and paramagnetic Fe-phthalocyanine having peripehral H atoms (FePc; S = 1). Tauc plot of the self-assembled FePc ZnFPc ensembles showed an optical band gap of ?1.05 eV and temperature-dependent current-voltage (I-V) studies suggest semiconducting characteristics in the material. Using DFT+U quantum-chemical calculations, we reveal the origin of such unusual ferromagnetic exchange-interaction in the supramolecular FePc ZnFPc system. 2016 American Chemical Society.
Possible Room-Temperature Ferromagnetism in Self-Assembled Ensembles of Paramagnetic and Diamagnetic Molecular Semiconductors
(American Chemical Society service@acs.org, 2016) Dhara, B.; Tarafder, K.; Jha, P.K.; Panja, S.N.; Nair, S.; Oppeneer, P.M.; Ballav, N.
Owing to long spin-relaxation time and chemically customizable physical properties, molecule-based semiconductor materials like metal-phthalocyanines offer promising alternatives to conventional dilute magnetic semiconductors/oxides (DMSs/DMOs) to achieve room-temperature (RT) ferromagnetism. However, air-stable molecule-based materials exhibiting both semiconductivity and magnetic-order at RT have so far remained elusive. We present here the concept of supramolecular arrangement to accomplish possibly RT ferromagnetism. Specifically, we observe a clear hysteresis-loop (Hc ? 120 Oe) at 300 K in the magnetization versus field (M-H) plot of the self-assembled ensembles of diamagnetic Zn-phthalocyanine having peripheral F atoms (ZnFPc; S = 0) and paramagnetic Fe-phthalocyanine having peripehral H atoms (FePc; S = 1). Tauc plot of the self-assembled FePc···ZnFPc ensembles showed an optical band gap of ?1.05 eV and temperature-dependent current-voltage (I-V) studies suggest semiconducting characteristics in the material. Using DFT+U quantum-chemical calculations, we reveal the origin of such unusual ferromagnetic exchange-interaction in the supramolecular FePc···ZnFPc system. © 2016 American Chemical Society.
Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications
(2017) Pangannaya, S.; Purayil, N.P.; Dabhi, S.; Mankad, V.; Jha, P.K.; Shinde, S.; Trivedi, D.R.
New colorimetric receptors R1 and R2 with varied positional substitution of a cyano and nitro signaling unit having a hydroxy functionality as the hydrogen bond donor site have been designed, synthesized and characterized by FTIR, 1H NMR spectroscopy and mass spectrometry. The receptors R1 and R2 exhibit prominent visual response for F- and AcO- ions allowing the real time analysis of these ions in aqueous media. The formation of the receptor-anion complexes has been supported by UV-vis titration studies and confirmed through binding constant calculations. The anion binding process follows a first order rate equation and the calculated rate constants reveal a higher order of reactivity for AcO- ions. The 1H NMR titration and TDDFT studies provide full support of the binding mechanism. The Hg2+ and F- ion sensing property of receptor R1 has been utilized to arrive at "AND" and "INHIBIT" molecular logic gate applications. 2017 Pangannaya et al.; licensee Beilstein-Institut.
Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications
(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften info@beilstein-institut.de, 2017) Pangannaya, S.; Purayil, N.P.; Dabhi, S.; Mankad, V.; Jha, P.K.; Shinde, S.; Trivedi, D.R.
New colorimetric receptors R1 and R2 with varied positional substitution of a cyano and nitro signaling unit having a hydroxy functionality as the hydrogen bond donor site have been designed, synthesized and characterized by FTIR, 1H NMR spectroscopy and mass spectrometry. The receptors R1 and R2 exhibit prominent visual response for F- and AcO- ions allowing the real time analysis of these ions in aqueous media. The formation of the receptor-anion complexes has been supported by UV-vis titration studies and confirmed through binding constant calculations. The anion binding process follows a first order rate equation and the calculated rate constants reveal a higher order of reactivity for AcO- ions. The 1H NMR titration and TDDFT studies provide full support of the binding mechanism. The Hg2+ and F- ion sensing property of receptor R1 has been utilized to arrive at "AND" and "INHIBIT" molecular logic gate applications. © 2017 Pangannaya et al.; licensee Beilstein-Institut.