Design, synthesis, and application of a new series of organogelator using crystal engineering approach and solvent parameter study: A synergetic approach

Room-Temperature Phase Transition Material with Switchable Second-Order Nonlinear Optical Properties

Phase transition materials with switchable second-order nonlinear optical (NLO) properties have attracted extensive attention because of their great application potential in photoelectric switches, sensors, and modulators, while metal-free organics with NLO switchability near room temperature remain scarce. Herein, we report a hydrogen-bonded metal-free organic crystal, 2-methylpropan-2-aminium 2,2-dimethylpropanoate (1), exhibiting a room-temperature phase transition and favorable NLO switchability. Through investigations on its thermal anomalies, dielectric properties, and crystal structures, we uncover that 1 holds a near-room-temperature phase transition at 303 K from noncentrosymmetric point group C2v to centrosymmetric one D2h, which is attributed to the order-disorder transformations of both tert-butylamine cations and dimethylpropionic acid anions. Accompanied by symmetry change during the phase transition, 1 exhibits reversible and repeatable NLO "on-off" switchability with a desirable switching contrast ratio of ca. 19 between high and low NLO states. This discovery demonstrates a metal-free organic crystal with NLO switching behavior near room temperature, serving as a promising candidate in smart and ecofriendly photoelectric functional materials and devices.

Stimuli responsive gelation of tert-butylacetic acid based LMOGs - applications in remediation of marine oil spills, dye removal and heavy metal sensing

Tert-butylacetic acid based amides containing a structural backbone, a hydrogen bonding linker and a bulky end group have been synthesized (TBA1-TBA6) and explored for gelation of fuel oils and organic solvents. The importance of the tert-butyl group in driving the assembly towards gelation has been highlighted in our previously reported pivalamide-based phase selective organogelators (PSOGs). Both groups of compounds have been scrutinized and the effect of an additional methylene group in the newly synthesized series of compounds (on the gelation behavior, single crystal structure, non-covalent interactions responsible for gelation, morphology, dye absorption, etc.) were probed. Compounds TBA1-TBA6 were also utilized for sensing heavy metal ions and transition metal ions present in aqueous medium. They display phase-selective gelation of oil in the presence of biphasic systems (oil-sea water) when added in powder form as well as in solution form, and hence, make excellent candidates for containing oil spills in water bodies. Overall, both these libraries form a class of smallest molecules ever employed for successful organogelation behavior.

Computational Tools to Rationalize and Predict the Self-Assembly Behavior of Supramolecular Gels

Supramolecular gels form a class of soft materials that has been heavily explored by the chemical community in the past 20 years. While a multitude of experimental techniques has demonstrated its usefulness when characterizing these materials, the potential value of computational techniques has received much less attention. This review aims to provide a complete overview of studies that employ computational tools to obtain a better fundamental understanding of the self-assembly behavior of supramolecular gels or to accelerate their development by means of prediction. As such, we hope to stimulate researchers to consider using computational tools when investigating these intriguing materials. In the concluding remarks, we address future challenges faced by the field and formulate our vision on how computational methods could help overcoming them.