2D Cd(II)-MOF of Pyridyl-Imidazoquinazoline: Structure, Luminescence, and Selective Detection of TNP and Fabrication of Semiconducting Devices
Gurupada Bairy, Arka Dey, Basudeb Dutta, Partha Pratim Ray, Chittaranjan Sinha
Abstract
Pyridyl-substituted imidazoquinolines are highly fluorescent probes and are useful for the design of smart materials. A hitherto unknown pyridyl-imidazoquinazoline-coordinated two-dimensional (2D)-Cd(II)-MOF {[Cd2(5-nip)2(pdiq)2(H2O)2(CH3OH)]·H2O}n (CP 1), [H2nip = 5-nitroisophthalic acid and pdiq = 6-(pyridin-4-yl)-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline] has been designed and structurally confirmed by single-crystal X-ray crystallography. The presence of C–H···π and π···π interactions in CP 1 makes it a three-dimensional (3D) supramolecular structure. The excellent luminescent behavior of CP 1 is selectively quenched by trinitrophenol (TNP) even in the presence of potentially intrusive nitroaromatic explosives (NAEs). A limit of detection (LOD) of 2.75 × 10–7 M for TNP is achieved (3σ/m). In addition, the CP 1 displays electrical conductivity on an electronic device with the metal–semiconductor (MS) junction. Current vs voltage (I–V plot) correlation reveals the substantial enhancement of electrical conductivity upon illumination (Λ: 1.12 × 10–3 S m–1 (dark), 6.33 × 10–3 S m–1 (light)) along with a decrease in energy barrier (ΦB: 0.53 (dark), 0.42 (light)). The plots of log V vs log I show a non-Ohmic feature at a higher voltage (log V ≥ 0) both in the dark and the light phase, which is the characteristic of a Schottky diode barrier (SDB).