Tumpa Gorai

Development of artificial light harvesting systems in a minimalistic self‐assembly model is essential for the advancement of their functional scope within chemical and nanomaterial applications. In this work, we report bis‐naphthyl‐4‐hydroxy‐dipicolinic‐dicarboxamide (2‐DPA), a small molecule based aqueous nano‐dispersion as light harvesting medium for Förster resonance energy transfer (FRET) from greenish blue emitting Thioflavin T to orange emitting Pyronin Y and or Rhodamine B acceptor fluorophores. Efficient energy transfer was observed, as evidenced by emission, excitation, and lifetime studies. As well as their materials/morphological properties were probed using high‐resolution TEM and SEM, and confocal fluorescence microscopic imaging platforms. Furthermore, the Cucurbituril[7] host addition was found to have a significant impact on the energy transfer process, due to the formation of supramolecular host‐guest complexes with the Thioflavin T and Pyronin Y dyes, which resulted in the de‐assembly of multiple‐component FRET system.

Here we report the supramolecular organogels formation of two enantiomeric bisnaphthyl bipyridine diamide derivatives ( S/R ‐Bpy‐Nap) in organic solvents. Metallogelation studies were also performed for both enantiomers in tetrahydrofuran solvent. The gels were characterized by microscopy, spectroscopy, and rheology studies. The UV‐Vis absorption study showed selective binding of Co ²⁺ , Cu ^2+, and Ni ²⁺ with S/R‐Bpy‐Nap ligand, and circular dichroism (CD) spectral analysis exhibited a significant red shift in the CD signal in the presence of Ni ²⁺ , Co ²⁺ , and Cu ²⁺ ions. Thereafter, the preliminary investigation of the photocatalytic Rhodamine B dye degradation by Fe ³⁺ ‐S‐Bpy‐Nap xerogels was also explored in the presence of H ₂ O ₂ and blue LED (435‐445 nm) light irradiation. This work is directed towards the development of small molecule‐based gelators for interesting spectroscopic properties and environmental remediation applications.

Here, we report hierarchical self-assembly formation of luminescent Eu3+-1-DPA complex showing reversible thermoresponsive lanthanide centered emission, and in situ reversible esterification/hydrolysis responsive property was also demonstrated.

With the increased demand for green and sustainable sources of fuels, photocatalytic hydrogen gas production using semiconductor catalysts is attracting tremendous attention. In this perspective article, we will discuss the state-of-the-art development of small molecule-based semiconductors for photocatalytic green hydrogen production. Organic small molecules have the benefits of easy structural engineering allowing fine modulation of optical and electronic properties for the development of efficient photocatalysts. Small molecule-based photocatalyst development is advantageous compared to that of their polymer counterparts due to various reasons including less tedious synthesis, easily tunable optical and electronic properties, improved water dispersibility, etc. Conjugated donor–acceptor, porphyrin, perylene, and organic heterojunction nanoparticles are discussed in this article for their photocatalytic activity in the hydrogen evolution reaction. We have highlighted literature reports emphasizing the impact of heteroatom substitution, conjugation, band gap, exciton diffusion length, planarity, crystallinity, molecular packing, water solubility, etc. on photocatalytic performance.

The synthesis of a family of chiral and enantiomerically pure pyridyl‐diamide (pda) ligands that upon complexation with europium [Eu(CF₃SO₃)₃] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid‐state structures of these chiral metallosupramolecular systems are determined using X‐ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL‐LSCM) where the two enantiomers can be clearly distinguished.

Green luminescent microspheres, generated via charge-transfer interaction-induced hierarchical co-assembly of a bis-naphthyl dipicolinic amide derivative and tetracyanobenzene, transfer energy to long-wave emitting dye.

Here we report the synthesis of two morpholino-substituted naphthalimide ligands, N-(3-picolyl)-4-(1-morpholino)-1,8-naphthalimide L1 and N-benzyl-4-(1-morpholino)-1,8-naphthalimide L2, and study their supramolecular properties in the crystalline, solution and gel phases. These ligands were designed through incorporation of the morpholino group to enhance their photophysical and pH-responsive properties following recently reported N-(3-picolyl) naphthalimide metallogels. L1 was found to form metallogels on reaction with either Mn²⁺ or Co²⁺. The gels were found to be thermally and chemically responsive to various stimuli including pH. Conversely, L2 showed no reaction or coordination with transition metals, and did not gel under analogous conditions to L1. In the solution state, the fluorescence of both L1 and L2 exhibited pH responsiveness and counterion-influenced aggregation. The microparticle formation over the pH range was further investigated through Dynamic Light Scattering and Scanning Electron Microscopy. These two ligands illustrate how a modular ligand family can derive structure–function relationships and allow for systematic tuning, thus allowing for the future development of luminescent pH responsive soft materials.

The development of lanthanide based coordination polymer and metal–organic framework (CPs and MOFs) nanomaterials as novel functional (e.g. luminescent and magnetic) materials has attracted significant attention in recent times. This is in part due to the wide, but yet unique coordination requirements that the f-metal ions possess, as well as their attractive physical properties, which are often transferred to the bulk material. Hence, there is no surprise, that the design, synthesis and characterisation of lanthanide based CP/MOF materials (featuring either ‘pure’ lanthanides, or a mixture of both f- and d-metal ions) for applications in gas and small molecule absorption, storage, conversion/catalysis, chemical sensing, bio-imaging, drug delivery, etc. has been a prominent feature in the scientific literature. In this review, we give a selected overview of some of the recent developments in the area of Ln CP/MOF based nanomaterials for sensing, optical materials and bio-medicine research, as well as making reference to some more established examples, with the view of introducing, particularly to new researchers to the field, the powerful and attractive features of lanthanide based materials.

This work describes a terbium luminescence‐based protocol to selectively detect gallate‐derived green tea polyphenols on a supramolecular gel immobilised paper platform for the first time. This user‐friendly, inexpensive (€ 0.0015) approach requires very low sample volumes for the analysis. The developed strategy enables simultaneous detection of gallate polyphenols in multiple tea samples with the potential for practical applications.

Eu/Tb-based luminescent hydrogels and gel-coated discs were used for easy detection of alkaline phosphatase and β-galactosidase.