Kaushik Naskar

Cation dependent charge transport in linear dicarboxylate based isotypical 1D coordination polymers

Two new mixed-ligand one-dimensional coordination polymers (1D CPs) [Cd(adc)(4-phpy)2(H2O)2], (1) and [Zn(adc)(4-phpy)2(H2O)2], (2) (H2adc = acetylenedicarboxylic acid and 4-phpy = 4-phenylpyridine) have been synthesized and well characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). Both compounds 1 and 2 are isostructural and fabricate 3D supramolecular networks by the combination of hydrogen bonding and C–H⋯π interactions. Interestingly, these two materials exhibit electrical conductivity and reveal Schottky barrier diode behavior. To shed light on the charge transport mechanism of the compounds, the mobility, transit time, diffusion length and density of states at a quasi Fermi level have been derived. The analysis indicates that compound 1 has higher mobility (9.15 × 10−7 m2 V−1 s−1) and diffusion length (1.116 μm) in comparison to compound 2 (mobility and diffusion length are 5.44 × 10−7 m2 V−1 s−1 and 1.050 μm respectively). Compound 1, with the larger cation and shorter H-bonding distance, shows higher electrical conductivity, which is 2.55 times greater than compound 2.

Two isostructural linear coordination polymers: the size of the metal ion impacts the electrical conductivity

Two new one-dimensional coordination polymers (1D CPs) {[Zn(adc)(4-spy)2(H2O)2]}n (1), and {[Cd(adc)(4-spy)2(H2O)2]}n (2) (H2adc = acetylenedicarboxylic acid and 4-spy = 4-styrylpyridine), have been synthesized and well characterized. Single crystal X-ray diffraction data exhibit that compounds 1 and 2 are isostructural and undergo hydrogen bonding and C–H⋯π interactions to construct 3D supramolecular architectures. Electrical characterization reveals that both compounds show substantive electrical conductivity and exhibit Schottky diode nature. However, compound 2 has a higher mobility and higher conductivity compared to 1. The estimated values of effective carrier mobility, transit time, carrier concentration and diffusion length demonstrate that the charge transport properties have been improved for 2. Therefore, compound 2 has better performance in the fabrication of electronic devices.

Cu(II)-Based binuclear compound for the application of photosensitive electronic devices

In this study, an acetylenedicarboxylate based binuclear Cu(II) compound [Cu2(adc)(4-pic)6(H2O)4][ClO4]2 (1) (H2adc = acetylenedicarboxylic acid and 4-pic = 4-picolene) has been synthesized and well characterized using elemental analysis, infrared (IR) spectra, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) patterns and single crystal X-ray diffraction (SCXRD) techniques. The binuclear compound undergoes hydrogen bonding interactions to form a 1D hydrogen bonded aggregate, which further undergoes extensive edge-to-face C–H⋯π interactions to form a 3D supramolecular motif. The current conductivity of compound 1 was recorded under dark and illuminated conditions. Interestingly, the measured I–V characteristics of the synthesized material in the dark and under the illumination of incident light exhibit a highly non-linear rectifying behavior signifying a Schottky diode nature. Furthermore, the enhancement of values of the electrical parameters after exposure to illumination of incident radiation indicates the light sensing behaviour of the material. Therefore, the material can be used as a promising candidate in photosensitive electronic devices.

Use of rhodamine-allyl Schiff base in chemodosimetric processes for total palladium estimation and application in live cell imaging

Rhodamine derivatives are excellent fluorescent probes and have shown sharp descending trends of emission intensity on interaction with specific analytes, which causes opening of the spirolactam ring. In this study, rhodamine-allyl Schiff base (RD-2) is used as a highly sensitive colorimetric and fluorescent chemosensor for total palladium determination, and is indifferent to oxidation states (0,II,IV). The LOD is 95 nM. In addition, it is also a brilliant sensor for in vitro imaging of Pd2+ in RAW 264.7 (macrophage) cells. The probe RD-2 is structurally characterised by single-crystal X-ray diffraction measurement.