Photophysical characterizations of 2-(4-biphenylyl)-5 phenyl-1,3,4-oxadiazole in restricted geometry

Department of Physics, Tripura University, Ajarthala, Tripura, India
Journal of Luminescence (Impact Factor: 2.72). 01/2008; 128(1). DOI: 10.1016/j.jlumin.2007.05.001
Source: arXiv


Langmuir and Langmuir–Blodgett (LB) films of non-amphiphilic 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (abbreviated as PBD) mixed with stearic acid (SA) as well as with the inert polymer matrix poly(methyl methacrylate) (PMMA) have been studied. Surface pressure versus area per molecule (π–A) isotherm studies suggest that PBD molecules very likely stand vertically on the air–water interface and this arrangement allows the PBD molecules to form stacks and remain sandwiched between SA/PMMA molecules. At lower surface pressure, phase separation between PBD and matrix molecules occurs due to repulsive interaction. However, at higher surface pressure, PBD molecules form aggregates. The UV–vis absorption and steady-state fluorescence spectroscopic studies of the mixed LB films of PBD reveal the nature of the aggregates. H-type aggregate predominates in the mixed LB films, whereas I-type aggregate predominates in the PBD-PMMA spin-coated films. The degree of deformation produced in the electronic levels are largely affected by the film thickness and the surface pressure of lifting.

Download full-text


Available from: Syed Arshad Hussain,
70 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: To study the effect of aggregation of the 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) molecule in solid state, thin films of PBD have been prepared by the thermal evaporation technique onto glass and quartz substrates under different experimental conditions. These films have been studied for their structural, optical and electrical properties. AFM investigations of the films revealed that the films were smooth, dense and crack free with RMS roughness of 11–14 nm. XRD measurements indicate that films deposited on quartz are more crystalline than films deposited on glass substrate. Both absorption and reflectance spectra over the wavelength range 200–800 nm have been recorded to find optical parameters, namely, absorption, extinction coefficient, refractive index and dielectric constants. The inter-band transition energies are found to lie within the range 3.45–3.49 eV. Optical studies of the films indicate that PBD molecules preferred J-aggregation. A prominent single emission peak in the range of 370–390 nm has been observed which confirms that the fluorescent property of this molecule is not quenched in the thin film state. The electrical conductivity results for the evaporated films exhibited semiconductor behaviour within the investigated field and temperature range. The nature of the substrate is found to be a useful tool to modify the film morphology and for enhancing the charge transport within the films.
    Electronic Materials Letters 08/2012; 8(4). DOI:10.1007/s13391-012-2010-5 · 1.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A solution-processable functional polyimide, P(BPPO)-PI, containing oxadiazole moieties (electron donors) and phthalimide moieties (electron acceptors) was synthesized. A switching device, based on a solution-cast thin film of P(BPPO)-PI sandwiched between an indium−tin oxide (ITO) bottom electrode and an Al top electrode, exhibits two accessible conductivity states and can be switched from the low-conductivity (OFF) state to the high-conductivity (ON) state when swept positively or negatively, with an ON/OFF current ratio on the order of 1 × 104. The device exhibits ON state “remanence”, with the ON state retainable for a period of about 4 min after turning off the power. The ON state can be electrically sustained either by a refreshing voltage pulse of −1 V or by a continuous bias of −1 V. The “remanent” but volatile nature of the ON state and the ability to write, read, and sustain the electrical states with bias are characteristic features observed in a static random access memory (SRAM). The mechanisms associated with the memory effect were elucidated from molecular simulation results and changes in the photoelectronic spectrum of P(BPPO)-PI film when the device was switched between the ON and OFF states.
    Chemistry of Materials 07/2009; 21(14). DOI:10.1021/cm9010508 · 8.35 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Synthesis of novel 3-substituted-1,2,3-triazolo[1,5-a]quinazolinones in high yields was performed via anionic hetero-domino reaction of appropriate substituted 2-azidobenzoates prepared from isatines and acetonitriles activated by 1,3-thiazole, 1,3-benzothiazole, 1,3,4-oxadiazole, and 1,2,4-oxadiazole rings. It was shown that acetonitriles exhibited high reactivity and were convenient methylenic compounds for such reactions providing rapid structural variation.
    Journal of Heterocyclic Chemistry 03/2010; 47(2):415 - 420. DOI:10.1002/jhet.321 · 0.79 Impact Factor
Show more