47 research outputs found
A water soluble Ni-Schiff base complex for homogeneous green catalytic C S cross-coupling reactions
No full textSince the embarkation of C – S cross-coupling from aryl halides with thiols a handful of works have been
contemplated in aqueous medium. Herein, we report an example of a water soluble Ni-Schiff base complex as the green catalyst for the synthesis of thioethers. We have synthesized a Ni-Schiff base complex [NiL(H2O)2 ](ClO4)2 using N 4 -donor Schiff base ligand (1,3-bis(((E)-pyridin-2-ylmethylene)amino)propan-2-ol) and characterized by single crystal X-ray diffraction (SC-XRD) study along with different spectral analyses. The complex is mono-nuclear and cationic in nature having two perchlorate anions. Two water molecules remain coordinated with the Ni(II)-centre. The hydrogen bonding interaction through coordinated water and perchlorate anions connect the monomeric units to form 2D supramolecular structure. Based on its aqueous solubility, the complex has been used for the catalytic C – S cross-coupling reaction between aryl iodide and aryl or alkyl thiols using TBAB at 60 ◦ C in aqueous media (yield 92%). At room temperature, an isolated yield of 57% can be achieved. This environmentally benign protocol is paramount in view of the environmental sustainability
Simultaneous presence of mono- and bi-cationic bipyridyls within a metal-organic supramolecular host: crystal structure, spectral and Hirshfeld surface analysis
No full textA new supramolecular metal-organic complex, {[Fe(CN)6]3-(H2bipy)2+(Hbipy)+·3H2O} (where bipy ipywhere biolecular metal-organic complex, {[Fe(CN)ccepted: 30 October 2022rized by single crystal X-ray crystallographic study (SC-XRD), powder X-ray diffraction (PXRD) and other spectroscopic analysis. Structural analysis reveals that the complex crystallizes in monoclinic space group P21/c and is a 3 D supramolecular complex. Cyanide-water hydrogen bonding interactions between {Fe(CN)6}3- and guest water molecules form a wave-like 2 D supramolecular layer structure parallel to the crystallographic ac-plane with the formation of rectangular cavities of dimension 10.6 × 9.8 Å. These 2 D layers are further connected by O3W-H2W3···O1W hydrogen bonding interactions to form a 3 D supramolecular structure with the creation of 1 D supramolecular channels along the crystallographic a-axis. The bi-cationic (H2bipy)2+ form two different N+-H···water hydrogen bonding interactions (N8+-H8···O2W and N7+-H7···O3W) with two different water molecules and reside within the rectangular cavities. Monocationic (Hbipy)+ moieties form a 1 D supramolecular chain structure through repetitive N···H-N+ hydrogen bonding interactions and are present within the 1 D supramolecular channels. In addition, these two different types of bipy moieties are interconnected to each other through π···π interactions. Hirshfeld surface analysis and the corresponding 2 D fingerprint plots clearly identify the presence of different types of supramolecular interactions between the two differently charged bipyridyl moieties and the host framework, and N-H/H-N contacts, corresponding to the hydrogen bonding interactions, have a significant contribution to the total surface. Both the absorption and emission spectra of the complex have also been studied. </p
Multifunctional Interpenetrated 3D Supramolecular Structure Based on 1D Coordination Polymers: Selective Adsorption, Magnetism, Optical Property, Theoretical Analysis, and Electrical Conductivity
No full textA paddle-wheel-based multifunctional 1D coordination polymer (CP) {[Cu 2 (4-Cl-Bz) 4 (4,4′-bipy)](DMF) 2 } n (where 4-Cl-BzH = 4-chlorobenzoic acid, 4,4′-bipy = 4,4′-bipyridine, and DMF = dimethylformamide), (complex 1) have been synthesized via the solvothermal method and characterized by single-crystal X-ray diffraction analysis along with other spectroscopic studies. Structural analysis shows that 1 crystallizes in the tetragonal P4 /ncc space group and 1D coordination chains are formed by connecting [Cu 2 (4-Cl-Bz) 4 ] paddle wheel units using 4,4′-bipy moieties along the crystallographic c axis. These 1D coordination chains are assembled to each other through weak π···π interactions to form interpenetrated 3D supramolecular structure, forming channels along the [1 1 0] and [−1 1 0] direction hosting DMF molecules. Hirshfeld surface analysis and corresponding 2D fingerprint plots indicate that π···π interaction is the major interaction among the coordination chains. Thermal analysis shows that guest DMF molecules are released within the temperature range of 70−150 °C and powder X-ray diffraction (PXRD) analysis reveals the quenching of the void space after removal of the solvent molecules. The desolvated framework selectively adsorbs CO 2 over N 2 . The magneto-luminescent behavior of the framework has also been studied. This π-induced 3D supramolecular complex shows semiconducting behavior and conductivity increases upon desolvation
Pyridylenevinylene based Cu2+-specific, injectable metallo(hydro) gel: thixotropy and nanoscale metal-organic particles
No full textA Cu2+-selective metallo(hydro) gelation of a p-pyridyl ended oligophenylenevinylene system is reported over its respective meta- and ortho-regioisomers. The metallogel formed via the self-assembly of the nanoscale-metal-organic particles is injectable and also shows multi-stimuli responsiveness, including thixotropy
Remarkable Role of C-I center dot center dot center dot N Halogen Bonding in Thixotropic `Halo'gel Formation
No full textHalogen-bonding-induced self-assembly in the solution of equimolar mixtures of certain pyridyl-ended oligo p-phenylenevinylene (OPV)-derivatives with 1,4-diiodotetra-fluorobenzene is reported. The mode of self-assembly, that is, cocrystallization, thixotropic gelation, or precipitation, depends strongly on the nature of chains (n-alkyl chains as a function of length or short oxyethylene chain) appended to the OPV-backbone as well as on the cooling rate of the corresponding hot solution. Single-crystal X-ray diffraction studies of the cocrystals reveal the ``infinite'' chain formation via C-I center dot center dot center dot N halogen-bonding interactions between the two components. In addition, multiple noncovalent interactions induce cross-links among these halogen-bonded ``infinite'' chains. Interestingly, the molecular packing in the ``Cogel'' bearing OPV-derivative with oxyethylene chains is found to be very similar to that of the cocrystal of the same
Charge Transfer Induces Formation of Stimuli-Responsive, Chiral, Cohesive Vesicles-on-a-String that Eventually Turn into a Hydrogel
No full textA charge transfer (CT) mediated two-component, multistimuli responsive supergelation involving a L-histidine-appended pyrenyl derivative (PyHisOMe) as a donor and an asymmetric bolaamphiphilic naphthalene-diimide (Asym-NDI) derivative as an acceptor in a 2: 1 mixture of H2O/MeOH was investigated. Asym-NDI alone self-assembled into pH-responsive vesicular nanostructures in water. Excellent selectivity in CT gel formation was achieved in terms of choosing amino acid appended pyrenyl donor scaffolds. Circular di-chroism and morphological studies suggested formation of chiral, interconnected vesicular assemblies resembling ``pearls-on-a-string'' from these CT mixed stacks. XRD studies revealed the formation of monolayer lipid membranes from these CT mixed stacks that eventually led to the formation of individual vesicles. Strong cohesive forces among the interconnected vesicles originate from the protrusion of the oxyethylene chains from the surfaces of the chiral vesicles
Phthalate mediated hydrogelation of a pyrene based system: a novel scaffold for shape-persistent, self-healing luminescent soft material
No full textTwo-component super-hydrogelation triggered by the acid-base interaction of a L-histidine appended pyrenyl derivative (PyHis) and phthalic acid (PA) was reported. The use of isomeric isophthalic or terephthalic acid or other comparable acids in place of PA does not lead to salt formation and therefore hydrogelation is not observed. Excimer formation of the pyrenyl unit has not been detected although the PyHis : PA = 1: 1 system undergoes extensive self-assembly in aqueous solution. The synergistic effect of intermolecular H-bonding forces, pi-pi stacking, electrostatic interactions, etc. is found to be responsible for robust hydrogel formation. Development of chiral supramotecular assemblies has been verified through circular dichroism spectroscopy. Morphological investigations involving the PyHis : PA = 1: 1 system show vesicular nano-structures with a definite bilayer width at relatively low concentrations. The latter fuses to construct coiled-coil left-handed helical fibers upon increase in the concentrations of the gelators. The intertwining of the resultant helical fibers eventually results in hydrogel formation. The probable bilayer packing in the self-assembled structures has been probed using X-ray diffraction (XRD) studies and lanthanide sensitization, which suggests that the polar imidazolium hydrogen phthalate unit of the gelator forms the head group and faces the hydrophilic water environment while the hydrophobic pyrenyl units sit inside the hydrophobic core of the bilayer. The hydrogel exhibits multi-stimuli responsiveness including thixotropic behavior. In addition, shape-persistent as well as rapid self-healing behaviour of the hydrogel was established. Furthermore load-bearing characteristics of the hydrogel have also been demonstrated
Orotic acid as a useful supramolecular synthon for the fabrication of an OPV based hydrogel: stoichiometry dependent injectable behavior
No full textA facile hydrogelation of a p-pyridylenevinylene derivative (PV) bearing oxyethylene chains in the presence of orotic acid (OA) occurs via various non-covalent interactions. Depending on the PV: OA molar ratio, the hydrogel shows vesicle to either cluster-type aggregate or fiber transformation. Visual color tuning, stimuli-responsiveness and injectable properties of the hydrogel are also observed
Role of synergistic pi-pi stacking and X-H center dot center dot center dot Cl (X = C, N, O) H-bonding interactions in gelation and gel phase crystallization
No full textThe self-assembly of p-pyridyl-ended oligo-p-phenylenevinylenes (OPVs) in ethanol leads to the formation of either hollow or solid microrods. The corresponding protonated OPVs with n-butyl chains induce transparent gelation and also gel phase crystallization owing to various synergistic noncovalent interactions. The chloride ion-selective gelation, AIEE and stimuli responsiveness of the gel are also observed
