A Cd(ii) based metal organic framework: a photosensitive current conductor

Explosive and pollutant nitroaromatic sensing through a Cd(II) based ladder shaped 1D coordination polymer

In the existing leanings of environmental and national security issues, establishment of appropriate sensors for explosive as well as pollutant nitroaromatic compounds may be considered as one of the most prodigious job for material researchers. In the current study a new Cd(II) based 1D ladder coordination polymer (CP), [Cd(4-bpd)(3-cbn)₂]_n, has been synthesized and well characterized through single crystal X-ray diffraction analysis. Interestingly, the supramolecular assembly of this compound has efficiently identified 2,4,6-trinitrophenol through fluorescence quenching method. The Stern-Volmer coefficient (K_sv) has been calculated as 6.047 × 10³ M^-1, which can be attributed to the quenching of the emission intensity. The limit of detection (LOD) has been determined as 0.260 μM following the 3σ method along with almost 95% fluorescence intensity reduction. FESEM study revealed that the crystalline nature of the compound has been altered upon interaction with the above mentioned nitroaromatic analyte. Theoretical studies were performed to get the insight idea of fluorescence quenching mechanism which also substantiated the experimental observation. The present study can pave the way for the fabrication of future generation technology in sensor field.

Conductive Metal-Organic Frameworks: Electronic Structure and Electrochemical Applications

Smarter and minimization of devices are consistently substantial to shape the energy landscape. Significant amounts of endeavours have come forward as promising steps to surmount this formidable challenge. It is undeniable that material scientists were contemplating smarter material beyond purely inorganic or organic materials. To our delight, metal-organic frameworks (MOFs), an inorganic-organic hybrid scaffold with unprecedented tunability and smart functionalities, have recently started their journey as an alternative. In this review, we focus on such propitious potential of MOFs that was untapped over a long time. We cover the synthetic strategies and (or) post-synthetic modifications towards the formation of conductive MOFs and their underlying concepts of charge transfer with structural aspects. We addressed theoretical calculations with the experimental outcomes and spectroelectrochemistry, which will trigger vigorous impetus about intrinsic electronic behaviour of the conductive frameworks. Finally, we discussed electrocatalysts and energy storage devices stemming from conductive MOFs to meet energy demand in the near future.

Mononuclear copper(ii) Schiff base complex: synthesis, structure, electrical analysis and protein binding study

A mononuclear copper(ii)-Schiff base complex has been explored for dual applications – complete electrical analysis and BSA protein binding study.

Electrically Conductive Metal-Organic Frameworks

Metal–organic frameworks (MOFs) are intrinsically porous extended solids formed by coordination bonding between organic ligands and metal ions or clusters. High electrical conductivity is rare in MOFs, yet it allows for diverse applications in electrocatalysis, charge storage, and chemiresistive sensing, among others. In this Review, we discuss the efforts undertaken so far to achieve efficient charge transport in MOFs. We focus on four common strategies that have been harnessed toward high conductivities. In the “through-bond” approach, continuous chains of coordination bonds between the metal centers and ligands’ functional groups create charge transport pathways. In the “extended conjugation” approach, the metals and entire ligands form large delocalized systems. The “through-space” approach harnesses the π–π stacking interactions between organic moieties. The “guest-promoted” approach utilizes the inherent porosity of MOFs and host–guest interactions. Studies utilizing less defined transport pathways are also evaluated. For each approach, we give a systematic overview of the structures and transport properties of relevant materials. We consider the benefits and limitations of strategies developed thus far and provide an overview of outstanding challenges in conductive MOFs.

Designing of Pb(II)-Based Novel Coordination Polymers (CPs): Structural Elucidation and Optoelectronic Application

[Pb₂(bdc)_1.5(aiz)] _n (1) and [Pb₂(bdc)_1.5(aiz)(MeOH)₂] _n (2) (H₂bdc = 1,4-benzene dicarboxylic acid, aiz = (E)-N'-(thiophen-2-ylmethylene)isonicotinohydrazide) have been synthesized, and structural characterization has been established by X-ray analysis and thermogravimetric analysis (TGA). Here, bdc^2- links two Pb(II) centers and the aiz ligand binds the metal centers in two different manners: chelating and monodonating. Thus, polymerizations have taken place from the combination of mixed ligand system. Optical band gaps have been studied via UV measurements. Again, the experimental and calculated (from density functional theory (DFT)) band gaps agree well and the semiconducting properties of synthesized polymeric materials have been approved. Thus, optoelectronic and photonic devices can be made by this type of coordination polymers (CPs). The I-V representative curves of 1 (device-A) and 2 (device-B) in both dark and illuminated conditions show that device-A has a higher magnitude of current than device-B. Dark- and photo-conductivity values of device-A are calculated as 2.94 × 10^-6 and 6.12 × 10^-6 S m^-1, respectively, whereas for device-B, the values of dark- and photo-conductivity are 2.92 × 10^-7 and 3.66 × 10^-7 S m^-1, respectively, at room temperature.

Tuning of the para-position of pyridyl ligands impacts the electrical properties of a series of Cd(ii) ladder polymers

This work describes the tuning of electrical nature of three Cd(ii)-based 1D coordination polymers by the modifications of para-substituent of pyridyl ligands.

Photosensitive Schottky barrier diode behavior of a semiconducting Co(iii)–Na complex with a compartmental Schiff base ligand

The opto-electronic properties of an X-ray characterized, end-to-end azide bridged cobalt(iii)–sodium complex, [(N₃)CoLNa(N₃)]_n, have been investigated in detail. The complex is found to be a direct semiconductor material as confirmed by determining the band gap of this complex by experimental as well as theoretical studies. The complex has also been used to construct a photosensitive Schottky device. Optical conductivity, calculated from the DFT study, has been used to analyze how the conductivity of the material changes upon illumination. The electrical conductivity and concomitantly, the photoconductivity of the material increase as a consequence of photon absorption.

The opto-electronic properties of a cobalt(iii)–sodium complex have been studied with the help of both experimental and theoretical investigation. The complex has also been used to fabricate an effective photosensitive Schottky device.

A tetranuclear nickel/lead complex with a salen type Schiff base: synthesis, structure and exploration of photosensitive Schottky barrier diode behaviour

A tetranuclear nickel(ii)/lead(ii) complex has been synthesized and characterized. The complex based device behaves as a Schottky diode. The charge transfer kinetics of the complex is enhanced after light soaking.

A Cd(ii)-based MOF as a photosensitive Schottky diode: experimental and theoretical studies

A Cd(ii) based 2D metal-organic framework (MOF), [Cd(4-bpd)(SCN)₂]_n (1) where 4-bpd = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, has been synthesized and characterized by standard methods including single crystal X-ray diffraction analysis. When it is sandwiched between ITO coated glass and Al, 1 shows interesting conduction properties. The I-V characteristics of the ITO/1/Al configuration measured in the dark and under illumination of incident light exhibit a highly non-linear rectifying behavior, which signifies its Schottky diode character. The conductivity of the configuration is 2.90 × 10^-4 S m^-1 and 7.16 × 10^-4 S m^-1 under dark and photoirradiation conditions, respectively. Different parameters have been analyzed and these indicate that 1 can be a promising candidate for light sensing electronic devices. This material has good sensitivity to the light source when switched on/off. Theoretical calculations have been performed to understand the reason for the enhancement of conductivity under illumination of incident light. It has been found that upon irradiation, slight changes in the bond distances of 4-bpd in 1 occur. These changes are related to the considerable decrease in the energy needed for the allowed electronic transition. This may influence the increase of conductivity along with other factors.

Electrical property and Schottky behavior of a flexible Schiff-base compound: X-ray structure and stabilization of 1D water chain

A flexible Schiff-base compound has been synthesized and structurally confirmed by X-ray crystallography. The compound behaves as a Schottky diode, as supported by the impedance spectroscopy.

Effect on Schottky behaviour of 1D coordination polymers by altering para-substituents on benzoate ligands

Schottky behaviour was tuned by altering para-substituents on benzoate ligands in two isostructural Zn(ii)-based 1D coordination polymers.

Mono-, tri- and polynuclear copper(ii) complexes of Schiff-base ligands: synthesis, characterization and catalytic activity towards alcohol oxidation

A mononuclear copper(ii) complex acts as a superior catalyst compared to a tri- or polynuclear complex towards oxidation of alcohols to the corresponding aldehydes.

A Ni-based MOF for selective detection and removal of Hg2+ in aqueous medium: a facile strategy

A Ni-based 3D MOF, [Ni(3-bpd)₂(NCS)₂]_n, where 3-bpd is 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene, has been explored for simultaneous detection and removal of Hg²⁺ in aqueous medium with excellent Hg uptake capacity.

Photoelectric properties and potential nitro derivatives sensing by a highly luminescent of Zn(ii) and Cd(ii) metal–organic frameworks assembled by the flexible hexapodal ligand, 1,3,5-triazine-2,4,6-triamine hexaacetic acid

The luminescent quenching of coordination polymers 1 and 2 were especially obvious with the increasing of the nitro derivatives concentration, indicating 1 and 2 have very high sensitivity sensing properties.