Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles.

Supra-amphiphiles constituted of noncovalent bonds have emerged as attractive systems for fabrication of stimuli-responsive self-assembled nanostructures. A unique supramolecular strategy utilizing halogen (X)-bonding interaction has been demonstrated for constructing emissive supra-π-amphiphiles in water from a hydrophobic pyridyl functionalized naphthalene monoimide (NMI-Py) based X-bond acceptor and hydrophilic iodotetrafluorophenyl functionalized polyethylene glycol (PEG-I) or triethylene glycol (TEG-I) based X-bond donors, while their luminescent higher ordered assemblies were governed by orthogonal dipole-dipole interaction and π-stacking of the NMI-Py fluorophore as probed by SCXRD and DFT calculations. Control molecules lacking iodotetrafluorophenyl moiety at the polyethylene glycol chain end failed to create any defined morphology from the NMI-Py, suggesting X-bonding is prerequisite for the nanostructure formation. Variation in the chain length of the X-bond donors leads to different morphologies (fiber vs vesicle) for PEG-I and TEG-I. Acid triggered denaturing of the X-bonds caused pH responsive disassembly of the thermally robust nanostructures. This strategy paves the way for facile fabrication of structurally diverse smart and adaptive luminescent functional materials with tunable morphology.

A Self-Healing Metal-Organic Hydrogel for an All-Solid Flexible Supercapacitor.

A zinc containing metal-organic gel (Zn-MOG) with embedded free ions, which exhibits self-healing properties, has been synthesized for application in supercapacitors. The activated carbon-based flexible supercapacitor device with the MOG electrolyte has a broad potential window of 2.1 V, with high retention of specific capacitance compared to the traditional polyvinyl alcohol (PVA)-based gel. The Zn-MOG does not require an additional electrolyte. The sodium and sulphate ions embedded in the MOG are sufficient enough for the charge storage.

Porous Metal-Organic Polyhedral Framework containing Cuboctahedron Cages as SBUs with High Affinity for H2 and CO2 Sorption: A Heterogeneous Catalyst for Chemical Fixation of CO2.

Development of active porous materials that can efficiently adsorb H2 and CO2 is needed, due to their practical utilities. Here we present the design and synthesis of an interpenetrated CuII metal-organic framework (MOF) that is thermally stable, highly porous and can act as a heterogeneous catalyst. The CuII -MOF contains a highly symmetric polyhedral metal cluster (Cu24 ) with cuboctahedron geometry as secondary building unit (SBU). The double interpenetration of such huge cluster-containing nets provides a high density of open metal sites, due to which it exhibits remarkable H2 storage capacity (313 cm3 g-1 at 1 bar and 77 K) as well as high CO2 capture ability (159 cm3 g-1 at 1 bar and 273 K). Further, its propensity towards CO2 sorption can be utilized for the heterogeneous catalysis of the chemical conversion of CO2 into the corresponding cyclic carbonates upon reaction with epoxides, with high turnover number and turnover frequency values.

Two Iron Complexes as Homogeneous and Heterogeneous Catalysts for the Chemical Fixation of Carbon Dioxide.

Two new bimetallic iron-alkali metal complexes of amino acid (serine)-based reduced Schiff base ligand were synthesized and structurally characterized. Their efficacy as catalysts for the chemical fixation of carbon dioxide was explored. The heterogeneous version of the catalytic reaction was developed by the immobilization of these homogeneous bimetallic iron-alkali metal complexes in an anion-exchange resin. The resin-bound complexes can be used as recyclable catalysts up to six cycles.

Self-assembling behavior of pyrimidine analogues: Unveiling the factors behind morphological diversity.

Studying the self-assembly of uracil derivatives has great importance in biochemistry and nanotechnology. Now, in order to architect unique and interesting nucleobase nanostructures, herein, we report a simple, yet robust uracil moiety based platform which is potentially capable to self-assemble into fibrils. The system is validated using eight uracil moiety derivatives and the effect is examined via fluorescence lifetime imaging microscopy (FLIM), field emission scanning electron microscopy (FESEM), steady state DCM fluorescence and fluorescence correlation spectroscopy (FCS). FLIM and FESEM give qualitative information regarding the fibril formation of different morphologies including string, rod, flower, needles etc. Steady state DCM fluorescence and FCS establish a quantitative estimation of the extent of fibril formation. The involvement of hydrogen bonding interaction between NH and CO groups in the fibrillar growth of 5-IU is evoked from the crystallographic study. Again, the key role of different functional groups behind the formation of fibrillar network is investigated through blocking the COO- group of orotic acid with lanthanides. Finally, esterification and N,N'-dimethylation exquisitely explore the role and priority of different groups in the fibril formation of pyrimidine analogues. The results may be useful for understanding the processes of self-assembly of the uracil derivatives and the rationalized design of the uracil based supramolecular structures with specific properties.

A copper(ii) metal-organic hydrogel as a multifunctional precatalyst for CuAAC reactions and chemical fixation of CO2 under solvent free conditions.

A copper(ii) metal-organic hydrogel has been synthesised and characterised. This hydrogel is an efficient, reusable precatalyst for CuAAC reactions and chemical fixation of CO2 under solvent free conditions.

Self-Healing and Moldable Metallogels as the Recyclable Materials for Selective Dye Adsorption and Separation.

Four multiresponsive and self-sustaining metallogels were synthesized by the reaction of the disodium salt of the ligand carboxymethyl-(3,5-di-tert-butyl-2-hydroxy-benzyl)amino acetic acid with Cd(II) and Zn(II) halides, which were found to show excellent selectivity for dye adsorption and separation, and one of the gels shows a rare self-healing property.