Dr. Gopal Singh | Florida International University (original) (raw)

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Papers by Dr. Gopal Singh

A new series of D–A–D molecules (1–3) with carbazole as a donor and 2,5-diaryl-1,3,4-oxadiazole, ... more A new series of D–A–D molecules (1–3) with carbazole as a donor and 2,5-diaryl-1,3,4-oxadiazole,
dibenzothiophene-S,S-dioxide and benzo[1,2,5]thiadiazole as acceptors have been synthesized. Polyphenylene
dendrons have also been incorporatedtopreventthefacetoface p–p stacking in aggregates. Unlike traditional
D–A systems, which show ACQ problems and large red shifts in the solid state, these derivatives (1–3) exhibit
good solid state luminescence behavior without undergoing a red shift or fluorescence quenching. The present
results indicate that just the combination of a donor–acceptor system with bulkier dendrons is not enough
to generate efficient solid state emissions but the prevention of co-facial interaction between donors and
acceptors in aggregates is more important. In the case of derivative 3, restriction of complete molecular
planarization and steric hindrance near the acceptor can effectively prevent intermolecular donor–acceptor
interactions, thus leading to enhanced emission in aggregates. While in the case of derivative 1, a sterically
unhindered acceptor is easily approached by a donor due to close molecular packing in aggregates
forming weakly luminescent species

Carbazole end-capped and triphenylamine centered starburst derivative TPA-Cz has been synthesised... more Carbazole end-capped and triphenylamine centered starburst derivative TPA-Cz has been synthesised. An
investigation into its various properties show that the derivative possesses excellent thermal and
morphological stability with stable amorphous behaviour, uniform surface morphology of ﬁlm
(rms roughness of 1.212 nm), low oxidation potential (5.2 eV) along with electrochemical stability, high
solubility and high transparency to visible light. All these properties clearly demonstrate that TPA-Cz is a
highly promising material that can be used as hole-transporting material in the electroluminescent
devices.

A series of blue fluorescent, 3,39-linked carbazole-based linear conjugated molecules (1–5) have ... more A series of blue fluorescent, 3,39-linked carbazole-based linear conjugated molecules (1–5) have been
synthesized with phenyl, ethynylene, and ethynylphenyl spacers. Their photophysical, electrochemical and
thermal properties have been studied to elucidate structure–property relationships. These chromophores
have a high thermal stability and exhibit high fluorescence quantum yields of the order of 0.98. In
addition, an OLED device was fabricated using compound 4 which shows bluish electroluminescence (CIE,
x = 0.25, y = 0.23).

) have been tested. Derivative 5
displays quite high through bond energy transfer eﬃciency in the presence of Hg2+
ions in methanol
whereas derivative 7 exhibits better FRET eﬃciency in the presence of Hg2+
ions in THF and CH3CN than
derivative 5.

A series of blue fluorescent, 3,39-linked carbazole-based linear conjugated molecules (1-5) have ... more A series of blue fluorescent, 3,39-linked carbazole-based linear conjugated molecules (1-5) have been synthesized with phenyl, ethynylene, and ethynylphenyl spacers. Their photophysical, electrochemical and thermal properties have been studied to elucidate structure-property relationships. These chromophores have a high thermal stability and exhibit high fluorescence quantum yields of the order of 0.98. In addition, an OLED device was fabricated using compound 4 which shows bluish electroluminescence (CIE, x = 0.25, y = 0.23).

Hexaphenylbenzene (HPB) derivatives 5 and 7 having rhodamine B moieties have been designed and sy... more Hexaphenylbenzene (HPB) derivatives 5 and 7 having rhodamine B moieties have been designed and synthesized, and have been shown to display solvent dependent. Fluorescence resonance energy transfer (FRET) and through bond energy transfer (TBET) in the presence of Hg 2+ ions among the various cations (Cu 2+ , Pb 2+ , Zn 2+ , Ni 2+ , Cd 2+ , Ag + , Ba 2+ , Mg 2+ , K + , Na + , and Li + ) have been tested. Derivative 5 displays quite high through bond energy transfer efficiency in the presence of Hg 2+ ions in methanol whereas derivative 7 exhibits better FRET efficiency in the presence of Hg 2+ ions in THF and CH 3 CN than derivative 5. † Electronic supplementary information (ESI) available: 1 H, 13 C, mass spectra, UV-vis and fluorescence spectra in different alcohols, equation for quantum yield. See

) have been tested. Derivative 5
displays quite high through bond energy transfer eﬃciency in the presence of Hg2+
ions in methanol
whereas derivative 7 exhibits better FRET eﬃciency in the presence of Hg2+
ions in THF and CH3CN than
derivative 5.