Herein, we have implemented an intimate grinding-mixing protocol (GMP) for the synthesis of a new hydrogelator from citrazinic acid and melamine. Ground mixture upon sonication, just for few second, in a suitable solvent/mixed-solvent system finally results in a gel matrix.Citrazinic acid, is decorated with ureidopyrimidone functionality and melamine is enriched with amino-pyridine functionality. Therefore, the necessary non-covalent interactions (like hydrogen bonding and π-π stacking) become a part-and-parcel, bringing a nanofibrous gel material in existence. A thorough and complete solvent dependent gelation investigation suggests that water must be present as the sole solvent or one of the members of other mixedsolvent system to successfully result in gel formation. The gel shows entangled network morphology. Different micro-analytical studies (FTIR, Powder XRD, FESEM, TEM, Rheology etc.) have been conducted for complete characterizations of the gel sample. The gel also exhibits its stimuli responsive behaviour towards different interfering chemical parameters like pH, selective anions etc. Again, it is worth mentioning that here GMP plays a key role to strongly initiate and improvise solid state self-assembly. Different non-covalent interactions procure the suitable hydrogen-bonded motif which presumably propagates upon activation in solution phase after mild sonication favouring spontaneous formation of fibrous architectures. It was also noticed that without grinding, the solid state interactions are jeopardized and only partial gel structure prevails. Finally the available porosity in the gel framework and the enriched π-electron density within, make the gel a suitable host for adsorption of guest molecules. This information provoked us to study the reversible adsorption-desorption equilibrium of molecular iodine within the dried-gel matrix. The guest, iodine entrapment into the host occurs both from the solution and also from gas phase iodine.The complete analysis suggests that our material presents a high storage capacity of this halogen species. Therefore the study prescribes that the synthesized hydrogel material could be a suitable candidate for application in synthetic organic chemistry and would find an avenue to solve other environmental issues also.Melamine and citrazinic acid, upon solid state grinding, produced a two-component gelator

This paper reports the adsorptive behavior of the 4-mercaptopyridine (4MPy) molecule soaked in gold nanoparticles (AuNPs) that remain embedded in the bilayer Langmuir–Blodgett (LB) film matrix of stearic acid (SA) for various soaking times (STs). The as-fabricated substrate proved to be an efficient SERS sensing platform that can sense the analyte 4MPy molecules at trace concentrations of ∼1.0 × 10 –9 M. The XPS study not only reveals the adsorption of 4Mpy molecules with AuNPs via a sulfur atom but also suggests partial degradation of the analyte molecule upon adsorption. This observation is further substantiated from the SERS spectral profile, which shows unusual broadening of the enhanced Raman bands of the molecule at higher STs. The experimental observations are supported by Born–Oppenheimer on-the-fly molecular dynamics (BO-OF-MD), time-resolved wavelet transform theory (WT), and the DFT calculations based on adcluster models. Selective enhancements of Raman bands in the SERS spectra further suggest the involvement of charge transfer (CT) interaction to the overall enhancements of Raman bands of the analyte molecule. The molecule → CT contribution has been estimated from electron density difference calculations and the corresponding CT distance; the amount of CT is also envisaged.

The conformational preferences of the industrially significant ethyl propionate (EP) molecule have been investigated from the Raman and FTIR spectra, aided by ab initio and Car-Parrinello molecular dynamics (CPMD) simulation studies. The vibrational signatures of various rotameric forms of the EP molecule have been assigned for the first time from the potential energy distributions (PEDs). The critical analyses of the vibrational signatures reveal the coexistences of the Trans-Trans (TT), Trans-Antigauche (TG(-)) [Trans-Gauche (TG(+))], Antigauche-Trans (G(-)T) [Gauche-Trans (G(+)T)], Antigauche-Antigauche (G(-)G(-)) [Gauche-Gauche (G(+)G(+))], and Gauche-Antigauche (G(+)G(-)) [Antigauche-Gauche (G(-)G(+))] forms of the EP molecule at room and at high temperatures. However, at low temperature (ca. 70 °C), the TT and TG(-) forms of the EP molecule is estimated to be preponderant. The Car-Parrinello molecular dynamics simulation studies of the EP molecule estimated at high, room, and low temperatures are also in harmony with our conjecture as suggested from the vibrational analyses. The ab intio molecular dynamics simulations are observed to be a useful tool for the conformational analyses of the molecule.

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Highly sensitive surface-enhanced Raman scattering active substrate obtained by self-assembly of silver nanocolloids (AgNCs) in the bilayer Langmuir-Blodgett (LB) film of stearic acid (SA) has been reported. Rhodamine 6G (R6G) has been used as the probe molecule to test the efficacy of the as prepared substrate. Gigantic enhancement factors~10 12 orders of magnitude have been estimated from the surface-enhanced resonance Raman scattering [SER(R) S] spectrum of R6G, which proves that the as prepared substrate is superior or comparable with silver nanoparticle as dried AgNC solutions on microscopic slides. The optical properties of the as prepared substrates have been envisaged by ultraviolet-visible absorption spectra, while their morphological features are mapped through field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images. A correlation has been drawn between the SER(R) S efficacy and the corresponding FESEM and AFM images of the as prepared substrates. Electric field distributions around the aggregated AgNCs have been estimated with the aid of three-dimensional finite difference time domain simulation studies. Localized surface plasmon coupling between the nanoaggregated geometries may be altered by lifting the LB film of SA at various surface pressures.