Light driven mesoscale assembly of a coordination polymeric gelator into flowers and stars with distinct properties

Control over the self-assembly process of porous organic–inorganic hybrids often leads to unprecedented polymorphism and properties. Herein we demonstrate how light can be a powerful tool to intervene in the kinetically controlled mesoscale self-assembly of a coordination polymeric gelator. Ultraviolet light induced coordination modulation via photoisomerisation of an azobenzene based dicarboxylate linker followed by aggregation mediated crystal growth resulted in two distinct morphological forms (flowers and stars), which show subtle differences in their physical properties

Supramolecular Gels and Functional Materials Research in India

Supramolecular gels are a class of soft materials made up of small molecules held together through non-covalent interactions. They have reversible properties and a wide range of applications. Chromophore-based gels are of particular interest due to their inherent electronic properties such as emission and charge transport useful for organic electronic device fabrication. Significant contributions have been made by Indian researchers in this area, which are highlighted in this mini review

Audible Sound Controlled Blue Bottle Experiment

The formation of chemical patterns is in general difficult to control due to the random diffusive motions of the reacting chemical species in solution. In this paper, we present a new method using audible sound to control the formation of chemical patterns obtained in blue bottle experiments. The waves generated on the surface of the solution by applying audible sound result in the nonuniform dissolution of atmospheric gases such as oxygen at the nodal and antinodal positions. On the basis of this phenomenon, the shapes of the patterns could be tuned according to the characteristics of the applied sound input, such as frequency and amplitude. This is an easy way for students to follow and control redox-responsive and pH-responsive chemical reactions in solution. The experiments involve chemicals that are mostly nontoxic and are easy to demonstrate since they involve common electronic gadgets (e.g., smartphones, Bluetooth speakers, etc.). These experiments provide interesting demonstration activities as well as a new understanding of utilizing audible sound for controlling chemical reactions. © 2022 American Chemical Society. All rights reserved.11Nsciescopu

Audible Sound Controlled Blue Bottle Experiment

© 2022 American Chemical Society and Division of Chemical Education, Inc.The formation of chemical patterns is in general difficult to control due to the random diffusive motions of the reacting chemical species in solution. In this paper, we present a new method using audible sound to control the formation of chemical patterns obtained in blue bottle experiments. The waves generated on the surface of the solution by applying audible sound result in the nonuniform dissolution of atmospheric gases such as oxygen at the nodal and antinodal positions. On the basis of this phenomenon, the shapes of the patterns could be tuned according to the characteristics of the applied sound input, such as frequency and amplitude. This is an easy way for students to follow and control redox-responsive and pH-responsive chemical reactions in solution. The experiments involve chemicals that are mostly nontoxic and are easy to demonstrate since they involve common electronic gadgets (e.g., smartphones, Bluetooth speakers, etc.). These experiments provide interesting demonstration activities as well as a new understanding of utilizing audible sound for controlling chemical reactions.11Nsciescopu

Porphyrin Boxes

In order to fabricate efficient molecular photonic devices, it has been a long-held aspiration for chemists to understand and mimic natural light-harvesting complexes where a rapid and efficient transfer of excitation energy between chlorophyll pigments is observed. Synthetic porphyrins are attractive building blocks in this regard because of their rigid and planar geometry, high thermal and electronic stability, high molar extinction, small and tunable band gap, and tweakable optical as well as redox behavior. Owing to these fascinating properties, various types of porphyrin-based architectures have been reported utilizing both covalent and noncovalent approaches. However, it still remains a challenge to construct chemically robust, well-defined three-dimensional porphyrin cages which can be easily synthesized and yet suitable for useful applications both in solution as well as in solid state. Working on this idea, we recently synthesized box-shaped organic cages, which we called porphyrin boxes, by making use of dynamic covalent chemistry of imine condensation reaction between 4-connecting, square-shaped, tetraformylporphyrin and 3-connecting, triangular-shaped, triamine molecules. Various presynthetic, as well as postsynthetic modifications, can be carried out on porphyrin boxes including a variation of the alkyl chain length in their 3-connecting subunit, chemical functionalization, and metalation of the porphyrin core. This can remarkably tune their inherent properties, e.g., solubility, window size, volume, and polarity of the internal void. The porphyrin boxes can therefore be considered as a significant addition to the family of multiporphyrin-based architectures, and because of their chemical stability and shape persistency, the applications of porphyrin boxes expand beyond the photophysical properties of an artificial light-harvesting complex. Consequently, they have been exploited as porous organic cages, where their gas adsorption properties have been investigated. By incorporating them in a lipid bilayer membrane, an iodide selective synthetic ion channel has also been demonstrated. Further, we have explored electrocatalytic reduction of carbon dioxide using Fe(III) metalated porphyrin boxes. Additionally, the precise size and ease of metalation of porphyrin boxes allowed us to utilize them as premade building blocks for creating coordination-based hierarchical superstructures. Considering these developments, it may be worth combining the photophysical properties of porphyrin with the shape-persistent porous nature of porphyrin boxes to explore other novel applications. This Account summarizes our recent work on porphyrin boxes, starting with their design, structural features, and applications in different fields. We also try to provide scientific insight into the future opportunities that these amazing boxes have in store for exploring the still uncharted challenging domains in the field of supramolecular chemistry in a confined space. © 2018 American Chemical Societ

Out-of-equilibrium chemical logic systems: Light- and sound-controlled programmable spatiotemporal patterns and mechanical functions

Living systems at different scales function through the sensing of multiple external signal inputs, which are further processed based on binary or more complicated computational models and networks. Inspired by such behavior, here, we show that the information processing in out-of-equilibrium chemical systems utilizing binary Boolean logic can be exploited to obtain transient functions such as spatiotemporally controlled chemical gradients and patterns in response to specific combination of multiple physical or chemical inputs (light, audible sound, and O-2). We further explore systems that are able to execute highly complicated functions such as guiding a cargo through a maze by processing the information from multiple external stimuli. Our approach of integrating and encoding binary Boolean logic within out-of-equilibrium chemical systems for the extraction of mechanical work to execute transient biomimicking functions can expand the realms of systems chemistry and related research and help us design smart materials.11Nsciescopu

Out-of-equilibrium chemical logic systems: Light- and sound-controlled programmable spatiotemporal patterns and mechanical functions

© 2022 Elsevier Inc.Living systems at different scales function through the sensing of multiple external signal inputs, which are further processed based on binary or more complicated computational models and networks. Inspired by such behavior, here, we show that the information processing in out-of-equilibrium chemical systems utilizing binary Boolean logic can be exploited to obtain transient functions such as spatiotemporally controlled chemical gradients and patterns in response to specific combination of multiple physical or chemical inputs (light, audible sound, and O2). We further explore systems that are able to execute highly complicated functions such as guiding a cargo through a maze by processing the information from multiple external stimuli. Our approach of integrating and encoding binary Boolean logic within out-of-equilibrium chemical systems for the extraction of mechanical work to execute transient biomimicking functions can expand the realms of systems chemistry and related research and help us design smart materials.11Nsci

Transient Self-assembly Processes Operated by Gaseous Fuels under Out-of-Equilibrium Conditions

© 2020 Wiley-VCH GmbH. Herein we report transient out-of-equilibrium self-assembly of molecules operated by gaseous fuel mixtures. The combination of an active gaseous chemical fuel and an inert gas or compressed air, which assists the degassing of the gaseous fuel from the solution, drives the transient self-assembly process. The gaseous nature of the fuel as well as the exhaust helps in their easy removal and thereby prevents their accumulation within the system and helps in maintaining the efficiency of the transient self-assembly process. The strategy is executed with a rather simple experimental set up and operates at ambient temperatures. Our approach may find use in the development of smart materials suitable for applications such as temporally active gas sensing and sequestration11sciescopu

Audible sound-controlled spatiotemporal patterns in out-of-equilibrium systems

© 2020, The Author(s), under exclusive licence to Springer Nature Limited. Naturally occurring spatiotemporal patterns typically have a predictable pattern design and are reproducible over several cycles. However, the patterns obtained from artificially designed out-of-equilibrium chemical oscillating networks (such as the Belousov–Zhabotinsky reaction for example) are unpredictable and difficult to control spatiotemporally, albeit reproducible over subsequent cycles. Here, we show that it is possible to generate reproducible spatiotemporal patterns in out-of-equilibrium chemical reactions and self-assembling systems in water in the presence of sound waves, which act as a guiding physical stimulus. Audible sound-induced liquid vibrations control the dissolution of atmospheric gases (such as O2 and CO2) in water to generate spatiotemporal chemical patterns in the bulk of the fluid, segregating the solution into spatiotemporal domains having different redox properties or pH values. It further helps us in the organization of transiently formed supramolecular aggregates in a predictable spatiotemporal manner. [Figure not available: see fulltext.11sciescopu

Fuel-Driven Transient Crystallization of a Cucurbit[8]uril-Based Host-Guest Complex

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimTransient self-assembling systems often suffer from accumulation of chemical wastes that interfere with the formation of pristine self-assembled products in subsequent cycles. Herein, we report the transient crystallization of a cucurbit[8]uril-based host-guest complex, preventing the accumulation of chemical wastes. Base-catalyzed thermal decarboxylation of trichloroacetic acid that chemically fuels the crystallization process dissolves the crystals, and produces volatile chemical wastes that are spontaneously removed from the solution. With such self-clearance process, no significant damping in the formation of the crystals was observed. The morphology and structural integrity of the crystals was also maintained in subsequent cycles. The concept may be further extended to obtain other temporally functional materials, quasicrystals, etc., based on stimuli-responsive guest molecules11sciescopu