π-Systems and their Self-Assembly:
Our research team focuses on exploring the self-assembly mechanisms of π-conjugated systems and their applications in designing soft materials with tailored properties. π-conjugated molecules (oligo-p-phenylene vinylene/ethynylene/oligo-thiophenes, and so on) possess extended electron delocalization along their backbone, which endows them with unique electronic and optical properties. When these molecules are strategically designed to have long alkyl chains and hydrogen-bonding groups, they can spontaneously organize into ordered nanostructures through self-assembly processes, forming gels or other soft materials.
Understanding the self-assembly behavior of these π-conjugated materials are crucial for harnessing their potential in various fields such as light harvesting, optoelectronics, and smart materials. By investigating the molecular interactions, morphology evolution, and rheological properties during the self-assembly process, our team aims to elucidate the underlying principles governing the formation of these materials. Moreover, we seek to exploit this knowledge to engineer functional soft materials with tunable electronic, and optical properties, paving the way for innovative applications in optoelectronics, organic light-emitting devices, and beyond.
Self-assembled Functional Materials for Smart Coatings:
Our research team also delves into the intricate world of self-assembled functional materials, exploring their diverse applications across several critical domains. At the heart of our endeavors lies the quest to engineer superhydrophobic coatings capable of repelling water with unparalleled efficiency, promising advancements in various industries reliant on water resistance. By harnessing the principles of self-assembly, we aim to craft coatings that not only excel in repelling liquids but also possess enhanced durability and longevity.
Moreover, our research extends beyond mere water resistance, delving into the realm of security markers embedded within materials. Through ingenious design and meticulous experimentation, we strive to develop covert markers capable of thwarting counterfeit attempts and safeguarding the integrity of products and documents. Leveraging the versatility of self-assembly, these markers promise heightened levels of security, bolstering efforts to combat fraud and counterfeit operations. Furthermore, our exploration into self-assembled functional materials encompasses the development of advanced optical filters and smart windows. By harnessing the innate properties of materials at the nanoscale, we aspire to engineer optical filters capable of precise wavelength control, revolutionizing fields reliant on optical technologies.
Stimuli Responsive Materials
Another focus area of our research team is the development of stimuli-responsive materials for smart and practical applications. Over the past several years, we have specifically worked on (a) photoresponsive materials which change their state on light irradiation, e.g., (sol-gel) transition (Org. Lett. 2012), chirality switching (Angew. Chem. Int. Ed. 2012), Ostwald ripening of organic nano assemblies (J. Am. Chem. Soc. 2012); (b) thermoresponsive systems, which change their state and exhibit different properties at different temperatures, e.g., fluorescent materials for thermal writing (J. Am. Chem. Soc. 2009), self-erasable writing on paper using water as ink (Sci. Rep. 2015), controlled host-guest interaction (Nat. Commun. 2018), molecules exhibiting lower critical solution temperature (LCST) properties for smart windows (Angew. Chem. Int. Ed. 2022), thermochromic volatile memory and counter operations (Angew. Chem. Int. Ed. 2021) (c) electrochromic materials, which respond to electrical stimulus (ACS Appl. Mater. Interfaces, 2021 and 2022) (d) mechanoresponsive systems, which exhibit different optical response on application of mechanical stress (Chem. Sci. 2017).
Metallo-supramolecular Polymers
Among other non-covalent interactions, the group often exploits metal-ligand interactions to control the morphology of supramolecular polymers (Org. Lett. 2007; Chem. Sci. 2015) and develop materials for smart applications, e.g. superhydrophobic surfaces, which mimic the sticky hydrophobicity of rose petals and slippery hydrophobicity of lotus leaves (Angew. Chem. Int. Ed. 2017) and smart windows (Angew. Chem. Int. Ed. 2021).
Covalent Organic Frameworks (COF's)
One of the recent interests of the group is the synthesis of 2dimension (2D) nanomaterials (graphene analogues). In this regard, the group has explored 2D conjugated polymers and p-systems, widely popularized as covalent-organic frameworks (COFs). These materials have found applications in a wide variety of fields including gas storage, catalysis, electronics etc. Our group has utilized these materials for detection of nucleic acids (Angew. Chem. Int. Ed. 2018) and development of anti-bacterial surfaces (Angew. Chem. Int. Ed. 2020).
Sensors and Molecular Probes
Since 1998, we have been actively involved in developing chemosensors and molecular probes for the detection of various analytes, (Tetrahedron Lett. 39, 1795-1798). By fine-tuning the optical properties of π-systems, we have succeeded in creating both colorimetric and fluorescence-based systems responsive to multiple analytes. Our work includes foldamer-type colorimetric probes for Ca²⁺ ions (Angew. Chem. Int. Ed., 2002; J. Am. Chem. Soc., 2005), a ratiometric fluorescent probe for Zn²⁺ ions (J. Am. Chem. Soc., 2005), a ratiometric fluorescent probe for the detection of aminothiols in blood (Angew. Chem. Int. Ed., 2008), a specific fluorescent probe for cyanide ions in biosamples (Chem. Commun, 2010), and a fluorescent nanosensor for blood urea (Small, 2013), among others.