Adsorptive removal of heavy metals from wastewater using Cobalt-diphenylamine (Co-DPA) complex.

Heavy metals like Cadmium, Lead, and Chromium are the pollutants emitted into the environment through industrial development. In this work, a new diphenylamine coordinated cobalt complex (Co-DPA) has been synthesized and tested for its efficiency in removing heavy metals from wastewater, and its adsorption capacity was investigated. The effectiveness of heavy metals removal by Co-DPA was evaluated by adjusting the adsorption parameters, such as adsorbent dose, pH, initial metals concentration, and adsorption period. Heavy metal concentrations in real sample were 0.267, 0.075, and 0.125 mg/L for Cd2+, Pb2+, and Cr3+ before using as-synthesized Co-DPA to treat wastewater. After being treated with synthesized Co-DPA the concentration of heavy metals was reduced to 0.0129, 0.00028, 0.00054 mg/L for Cd2+, Pb2+, and Cr3+, respectively, in 80 min. The removal efficiency was 95.6%, 99.5%, and 99.5% for the respective metals. The adsorption process fitted satisfactorily with Freundlich isotherm with R2(0.999, 0.997, 0.995) for Cd2+, Pb2+, and Cr3+, respectively. The kinetic data obeyed the pseudo-second order for Cd2+ and Cr2+ and the pseudo-first order for Pb2+. Based on the results obtained within the framework of this study, it is concluded that the as-synthesized Co-DPA is a good adsorbent to eliminate heavy metal ions like Cd2+, Pb2+, and Cr3+from wastewater solution. In general, Co-DPA is a promising new material for the removal of heavy metal ions from water.

Revisiting organic charge-transfer cocrystals for wide-range tunable, ambient phosphorescence.

Simple and efficient designs that enable a wide range of phosphorescence emission in organic materials have ignited scientific interest across diverse fields. One particularly promising approach is the cocrystallization strategy, where organic cocrystals are ingeniously formed through relatively weaker and dynamic non-covalent interactions. In our present study, we push the boundaries further by extending this cocrystal strategy to incorporate donor-acceptor components, stabilized by various halogen bonding interactions. This non-covalent complexation triggers ambient, charge-transfer phosphorescence (3CT), which can be precisely tuned across a broad spectrum by a modular selection of components with distinct electronic characteristics. At the core of our investigation lies the electron-deficient phosphor, pyromellitic diimide, which, upon complexation with different donors based on their electron-donating strength, manifests a striking array of phosphorescence emission from CT triplet states, spanning from green to yellow to reddish orange accompanied by noteworthy quantum yields. Through a systematic exploration of the electronic properties using spectroscopic studies and molecular organization through single-crystal X-ray diffraction, we decisively establish the molecular origin of the observed phosphorescence. Notably, our work presents, for the first time, an elegant demonstration of tunable 3CT phosphorescence emission in intermolecular donor-acceptor systems, highlighting their immense significance in the quest for efficient organic phosphors.

Phosphorization Engineering on a MOF-Derived Metal Phosphide Heterostructure (Cu/Cu3P@NC) as an Electrode for Enhanced Supercapacitor Performance.

A highly conductive and rationally constructed metal-organic framework (MOF)-derived metal phosphide with a carbonaceous nanostructure is a meticulous architecture toward the development of electrode materials for energy storage devices. Herein, we report a facile strategy to design and construct a new three-dimensional (3D) Cu-MOF via a solvent diffusion method at ambient temperature, which was authenticated by a single-crystal X-ray diffraction study, revealing a novel topology of (2,4,7)-connected three-nodal net named smm4. Nevertheless, the poor conductivity of pristine MOFs is a major bottleneck hindering their capacitance. To overcome this, we demonstrated an MOF-derived Cu3P/Cu@NC heterostructure via low-temperature phosphorization of Cu-MOF. The electronic and ionic diffusion kinetics in Cu3P/Cu@NC were improved due to the synergistic effects of the heterostructure. The as-prepared Cu3P/Cu@NC heterostructure electrode delivers a specific capacity of 540 C g-1 at 1 A g-1 with outstanding rate performance (190 C g-1 at 20 A g-1) and cycle stability (91% capacity retention after 10,000 cycles). Moreover, the assembled asymmetric solid-state supercapacitor (ASC) achieved a high energy density/power density of 45.5 Wh kg-1/7.98 kW kg-1 with a wide operating voltage (1.6 V). Long-term stable capacity retention (87.2%) was accomplished after 5000 cycles. These robust electrochemical performances suggest that the Cu3P/Cu@NC heterostructure is a suitable electrode material for supercapacitor applications.

Heterostructures of MXenes and transition metal oxides for supercapacitors: an overview.

MXenes are a large family of two dimensional (2D) materials with high conductivity, redox activity and compositional diversity that have become front-runners in the materials world for a diverse range of energy storage applications. High-performing supercapacitors require electrode materials with high charge storage capabilities, excellent electrical conductivity for fast electron transfer, and the ability of fast charging/discharging with good cyclability. While MXenes show many of these properties, their energy storage capability is limited by a narrow electrochemically stable potential window due to irreversible oxidation under anodic potentials. Although transition metal oxides (TMOs) are often high-capacity materials with high redox activity, their cyclability and poor rate performance are persistent challenges because of their dissolution in aqueous electrolytes and mediocre conductivity. Forming heterostructures of MXenes with TMOs and using hybrid electrodes is a feasible approach to simultaneously increase the charge storage capacity of MXenes and improve the cyclability and rate performance of oxides. MXenes could also act as conductive substrates for the growth of oxides, which could perform as spacers to stop the aggregation of MXene sheets during charging/discharging and help in improving the supercapacitor performance. Moreover, TMOs could increase the interfacial contact between MXene sheets and help in providing short-diffusion ion channels. Hence, MXene/TMO heterostructures are promising for energy storage. This review summarizes the most recent developments in MXene/oxide heterostructures for supercapacitors and highlights the roles of individual components.

Room temperature charge-transfer phosphorescence from organic donor-acceptor Co-crystals.

Engineering the electronic excited state manifolds of organic molecules can give rise to various functional outcomes, including ambient triplet harvesting, that has received prodigious attention in the recent past. Herein, we introduce a modular, non-covalent approach to bias the entire excited state landscape of an organic molecule using tunable 'through-space charge-transfer' interactions with appropriate donors. Although charge-transfer (CT) donor-acceptor complexes have been extensively explored as functional and supramolecular motifs in the realm of soft organic materials, they could not imprint their potentiality in the field of luminescent materials, and it still remains as a challenge. Thus, in the present study, we investigate the modulation of the excited state emission characteristics of a simple pyromellitic diimide derivative on complexation with appropriate donor molecules of varying electronic characteristics to demonstrate the selective harvesting of emission from its locally excited (LE) and CT singlet and triplet states. Remarkably, co-crystallization of the pyromellitic diimide with heavy-atom substituted and electron-rich aromatic donors leads to an unprecedented ambient CT phosphorescence with impressive efficiency and notable lifetime. Further, gradual minimizing of the electron-donating strength of the donors from 1,4-diiodo-2,3,5,6-tetramethylbenzene (or 1,2-diiodo-3,4,5,6-tetramethylbenzene) to 1,2-diiodo-4,5-dimethylbenzene and 1-bromo-4-iodobenzene modulates the source of ambient phosphorescence emission from the 3CT excited state to 3LE excited state. Through comprehensive spectroscopic, theoretical studies, and single-crystal analyses, we elucidate the unparalleled role of intermolecular donor-acceptor interactions to toggle between the emissive excited states and stabilize the triplet excitons. We envisage that the present study will be able to provide new and innovative dimensions to the existing molecular designs employed for triplet harvesting.

Anion-π-Induced Room Temperature Phosphorescence from Emissive Charge-Transfer States.

The burgeoning noncovalent interactions between π-acidic aromatic surfaces and anions have been recently shown to have unique functional relevance in anion transport, ion sensing, and organocatalysis. Despite its potential to instigate charge-transfer (CT) states, modulation of the emission features by toggling between the excited states using anion-π interactions is not yet explored. On the other hand, excited states with CT characteristics play an important role in the ambient triplet harvesting of organic chromophores. In this context, herein we propose an anion-π-based molecular design for the introduction of emissive singlet and triplet CT excited states, thereby expanding the functional scope of these weak supramolecular interactions. In the present study, we investigate the anion-π-induced emission from the singlet (1CT) and triplet (3CT) CT states of a dibromo dicationic pyromellitic diimide derivative. Remarkably, we accomplish dual room temperature phosphorescence emission from the anion-π-mediated 3CT state along with the locally excited triplet state (3LE) in solution phase using an organic-inorganic supramolecular scaffolding strategy. Comprehensive steady-state and time-resolved spectroscopy along with theoretical calculations provide detailed insights into the excited-state manifolds of phosphor. We envisage that the present study will expedite new molecular designs based on weak intermolecular interactions for the excited-state engineering of organic chromophores to facilitate ambient triplet harvesting and CT emission.

Recent highlights and future prospects on mixed-metal MOFs as emerging supercapacitor candidates.

Mixed-metal metal-organic frameworks (M-MOFs) consist of at least two different metal ions as nodes in the same framework. The incorporation of a second or more metal ions provides structural/compositional diversity, multi-functionality and stability to the framework. Moreover, the periodical array of different metal ions in the framework may alter the physical/chemical properties of M-MOFs and result in fascinating applications. M-MOFs with exciting structural features offer superior supercapacitor performances compared to single metal MOFs due to the synergic effect of different metal ions. In this review, we summarize several synthetic methods to construct M-MOFs by employing various organic ligands or metalloligands. Further, we discuss the electrochemical performance of several M-MOFs and their derived composite materials for supercapacitor applications.

Crystallographic Elucidation of Stimuli-Controlled Molecular Rotation for a Reversible Sol-Gel Transformation.

To get an idea about the most probable microporous supramolecular environment in the gel state, gelator molecule 1 has been crystallized from its gelling solvent (dimethylformamide). Crystal structure analysis of 1 shows a strong π···π stacking interaction between the electron-deficient pentafluorophenyl ring and electron-rich naphthyl ring. The gelling solvent situated in the "molecular pocket" stitches the gelators through weak H-bonding interactions to facilitate the formation of an organogel. Scanning electron microscopy analysis exhibits a ribbonlike fibrous morphology that resembles the supramolecular arrangement of 1 in its crystalline state, as evidenced by powder X-ray diffraction. In the presence of external stimuli (tetrabutylammonium fluoride), the organogel of 1 disassembles into sol. This sol-gel transformation phenomenon has been explained on the basis of X-ray single-crystal analysis. Single crystals obtained from the sol state show that naphthylic -OH of 1 gets deprotonated, resulting in C-C bond rotation that plays a major role in the sol-gel transformation. Gelator 1 exhibits weak green fluorescence in the gel state, whereas it shows highly intense yellow fluorescence in the sol state. Furthermore, a reversible sol-gel transformation associated with changes in the spectroscopic properties has been observed in the presence of acids and fluoride ions, respectively.

Design and Construction of Aroyl-Hydrazone Derivatives: Synthesis, Crystal Structure, Molecular Docking and Their Biological Activities.

Here, we report the synthesis and characterization of four new aroyl-hydrazone derivatives L1 -L4 , and their structural as well as biological activities have been explored. In addition to docking with bovine serum albumin (BSA) and duplex DNA, the experimental results demonstrate the effective binding of L1 -L4 with BSA protein and calf thymus DNA (ct-DNA) which is in agreement with the docking results. Further biological activities of L1 -L4 have been examined through molecular docking with different proteins which are involved in the propagation of viral or cancer diseases. L1 shows best binding affinity with influenza A virus polymerase PB2 subunit (2VY7) with binding energy -11.42 kcal/mol and inhibition constant 4.23 nm, whereas L2 strongly bind with the hepatitis C virus NS5B polymerase (2WCX) with binding energy -10.47 kcal/mol and inhibition constant 21.06 nm. Ligand L3 binds strongly with TGF-beta receptor 1 (3FAA) and L4 with cancer-related EphA2 protein kinases (1MQB) with binding energy -10.61 kcal/mol, -10.02 kcal/mol and inhibition constant 16.67 nm and 45.41 nm, respectively. The binding energies of L1 -L4 are comparable with binding energies of their proven inhibitors. L1 , L3 and L4 can be considered as both 3FAA and 1MQB dual targeting anticancer agents, while L1 and L3 are both 2VY7 and 2WCX dual targeting antiviral agents. On the other side, L2 and L4 target only one virus related target (2WCX). Furthermore, the geometry optimizations of L1 -L4 were performed via density functional theory (DFT). Moreover, all four ligands (L1 -L4 ) were characterized by NMR, FT-IR, ESI-MS, elemental analysis and their molecular structures were validated by single crystal X-ray diffraction studies.

Catalytic CO2 Fixation over a Robust Lactam-Functionalized Cu(II) Metal Organic Framework.

A porous, Cu(II)-metal organic framework (Cu-MOF) constituted of a rigid lactam functionalized ditopic ligand (H2L) was synthesized at room temperature under slow evaporation conditions {H2L = (5-(1-oxo-2,3-dihydro-1H-inden-2-yl)isophthalic acid)}. The single crystal X-ray structure revealed the formation of a 3D framework of Cu-MOF with one-dimensional (1D) channels decorated with lactam groups and exposed metal centers in the crystallographic c-axis. Interestingly, Cu(II) coordinated DMF molecules were eliminated from the Cu(II) metal center on activation of Cu-MOF at a temperature of 150 °C under high vacuum to generate a solvent free framework with pores lined with unsaturated Lewis acidic Cu(II) ions, i.e., Cu-MOF'. The lactam functionalized channels inclined toward the CO2, which interact with the Cu(II) metal sites lined in the channels of Cu-MOF' and exhibit fascinating solvent-free heterogeneous catalytic conversion of CO2 to cyclic carbonates at atmospheric pressure of CO2, under mild conditions. Furthermore, the Cu-MOF' catalyst was easily recycled and reused for several cycles without a significant loss in catalytic activity.

Functionalized Cu-MOF@CNT Hybrid: Synthesis, Crystal Structure and Applicability in Supercapacitors.

The synthesis of a metal-organic framework (MOF) named IITI-1 is reported by employing an H2 L linker with Cu(NO3 )2 ⋅3 H2 O in a mixed solvent system of N,N-dimethyl formamide (DMF) and H2 O. Further, in order to explore the energy storage application of IITI-1, a IITI-1/CNT hybrid was prepared by a simple ultrasonication technique. Incorporation of a carbon nanotube (CNT) in the layered IITI-1 MOF gave rise to enhanced electrolyte accessibility along with improved electrochemical storage capacity. The electrochemical investigations reveal a high specific capacitance (380 F g-1 at 1.6 A g-1 ) with a good rate performance for IITI-1/CNT. The IITI-1 MOF and the IITI-1/CNT composite were characterized by PXRD, BET, SEM, and TEM techniques. Moreover, IITI-1 MOF was also confirmed by single-crystal XRD analysis.

Mixed-Ligand-Architected 2D Co(II)-MOF Expressing a Novel Topology for an Efficient Photoanode for Water Oxidation Using Visible Light.

The structural diversity of Co(II) metal centers is known to influence their physicochemical properties. A novel two-dimensional (2D) Co(II)-MOF {[Co5(HL)4(dpp)2(H2O)2(µ-OH)2]·21H2O} n has been designed and synthesized by adopting a mixed-ligand strategy, using 1,3-di(4-pyridyl)propane (dpp) colinker with a flexible spacer H3L (H3L: 5-(2 carboxybenzyloxy)isophthalic acid). Co(II)-MOF features a 2D network, which is further interpenetrated among the equivalent sets and therefore results in a 3D supramolecular network. Topologically, the entire network can be viewed as a (3,4,8)-connected three-nodal net with the extended point symbol of {4.5.7}4{412.52.710.94}{52.8.92.10}2, duly assigned to the novel topological type smm2. The functional utility of Co(II)-MOF is demonstrated by employing it toward oxygen evolution reaction (OER) in a photoelectrochemical cell, exhibiting appreciable photocurrents of up to 5.89 mA/cm2 when used as an anode in a photoelectrochemical cell, while also displaying encouraging electrocatalytic currents of 9.32 mA/cm2 (at 2.01 V vs RHE) for the OER. Moreover, detailed electrochemical impedance spectroscopy studies confirm enhanced charge-transfer kinetics and improved conductivity under illumination with minimal effect of interfacial phenomena. This work provides a reference for the expanding field of research into applications of MOF materials and establishes MOF materials as favorable candidates for sustainable and efficient design of electrodes for water splitting.

A novel mesoionic carbene based highly fluorescent Pd(ii) complex as an endoplasmic reticulum tracker in live cells.

A recent study advocates that endoplasmic reticulum (ER) dysfunction may be linked to critical neurotrauma and advanced tauopathy. In this regard, targeting the ER warrants urgent attention towards the therapeutic treatment of neurotrauma-related neurodegeneration. Herein, we report the synthesis of a new N-heterocyclic mesoionic carbene based highly fluorescent square-planar Pd(ii) complex 1, with a high quantum yield (0.737). Probe 1 is a non-toxic probe for selectively labeling the endoplasmic reticulum in live cells.