Mukhtar Ali

Photo-organic field effect transistor based on a metalloporphyrin

We report the effect of light on the output characteristics of the organic field effect transistor fabricated by using the 5,10,15,20-Tetrakis(3 � ,5 � -di-tertbutylphenyl)porphyrinatocopper(II) (TDTPPCu) as a channel material and demonstrate light for controlling the drain‐source current instead of the gate voltage. Upon illumination, a detectable change in the drain‐source current was observed.

THE SENSING OF HUMIDITY BY SURFACE-TYPE Ag/FORMYL-TIPPCu(II)/Ag SENSOR FOR ENVIRONMENTAL MONITORING

In this paper, we have studied the effects of changing relative humidity on the electrical parameters and their multi frequency response of the surface type Ag/formyl-TIPPCu(II)/Ag humidity sensors. The silver electrodes of thickness 100 nm were primarily deposited on cleaned glass substrates by thermal evaporator. A gap of 40 μm was created between the electrodes of each device by using mask during the evaporation process. Thin films of formyl-TIPPCu(II) of 140 nm thickness were grown on silver electrodes by thermal sublimation technique. The values of capacitance and resistance of the sensors were found at different humidity levels at frequency of 1, 10 and 100 kHz of AC input signal. A remarkable increase in capacitance and decrease in resistance were observed during the rise of relative humidity from 45% to 95% RH. The hysteresis response of these humidity sensors was also studied at 1 kHz AC signal.

Temperature dependant electrical properties of formyl-TIPPCu(II)/p-Si heterojunction diode

This paper reports the temperature dependent electrical characterization of formyl-TIPPCu(II)/p-Si heterojunction diode which was fabricated by growing thin films of formyl-TIPPCu(II) on the p-type silicon substrate by thermal sublimation technique. The variation in electrical characteristics of the fabricated devices has been systematically investigated as the function of temperature by using current–voltage (I–V) measurements in the temperature range 299–339 K. The diode parameters like ideality factor, zero bias barrier height and parasitic series resistance have been found to be strongly temperature dependant. The zero bias barrier height increases while ideality factor and series resistance decreases with increasing temperature.

Halo-Wittig- and zirconium-promoted synthesis of conjugated metalloporphyrin dimers

The synthesis and spectroscopic studies of metalloporphyrin dimers having 1,3-butadiyne linker attached to the beta pyrrolic positions of the linked porphyrins are reported. Bromoethenyl metalloporphyrins were synthesized by zirconocene-promoted bromomethylenation of beta formyl metalloporphyrins. Bromoethenyl metalloporphyrins were dehydrohalogenated by potassium tert-butoxide to give beta ethynyl or 2-ethynyl metalloporphyrins. It is the first documented example of zirconocene-promoted bromomethylenation of beta formyl metalloporphyrins. Bromoethenyl metalloporphyrins were also synthesized by halo-Wittig route. 2-ethynyl metalloporphyrins were self dimerized to give metalloporphyrin dimers having 1,3-butadiyne linking bridge. FTIR, Raman spectroscopy, UV-visible, elemental analysis, 1H NMR and mass spectrometry were used to characterize the compounds.