Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area B1,500 m 2 g À 1 ), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 mmol g À 1 of trypsin.

Covalent organic nanosheets (CONs) were synthesised from imide functionalised COFs. TfpBDH-CONs exhibit a "turn-on" detection capability for 2,4,6-trinitrophenol in the solid state, but show a "turn-off" detection in the dispersion state.

A photoactivatable dopamine-conjugated platinum(IV) anticancer complex (Pt-DA) has been incorporated into G-quadruplex GK borate hydrogels by using borate ester linkages (Pt-GKB hydrogel). These were characterized by B NMR, attenuated total reflection Fourier transform infrared spectroscopy, circular dichroism, scanning electron microscopy and transmission electron microscopy. Microscopy investigations revealed the transformation of an extended fiber assembly into discrete flakes after incorporation of Pt-DA. Pt-DA showed photocytotoxicity against cisplatin-resistant A2780Cis human ovarian cancer cells (IC 74 μM, blue light) with a photocytotoxic index <2, whereas Pt-GKB hydrogels exhibited more potent photocytotoxicity (IC 3 μM, blue light) with a photocytotoxic index >5. Most notably, Pt-DA and Pt-GKB hydrogels show selective phototoxicity for cancer cells versus normal fibroblast cells (MRC5).

We report facile one-pot synthesis of water-soluble green fluorescent gold nanoclusters (AuNCs), capped with 8-mercapto-9-propyladenine. The synthesized AuNCs were characterized by Fourier transform infrared (FTIR), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), (1)H NMR, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. These nanoclusters show high photostability and biocompatibility. We observed that AuNCs stain cell nuclei with high specificity, where the mechanism of AuNC uptake was established through pathway-specific uptake inhibitors. These studies revealed that cell internalization of AuNCs occurs via a macropinocytosis pathway.

In the context of designing novel amino acid nanostructures, the capacity of tyrosine alone to form well-ordered structures under different conditions was explored. It was observed that Tyr can self-assemble into well-defined morphologies when deposited onto surfaces for transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. The influence of various parameters that can modulate the self-assembly process, including concentration of the amino acid, aging time, and solvent, was studied. Different supramolecular architectures, including nanoribbons, branched structures, and fern-like arrangements were also observed.

We demonstrate a novel strategy to synthesize highly stable and luminescent mercaptoimidazole-capped copper nanoclusters (CuNCs). Simple modification of substituents on the mercaptoimidazole ligand dictates the self-assembly and photophysical properties of the clusters.

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Single-walled carbon nanotubes (SWCNTs) have been covalently functionalized with uracil nucleobase. The hybrids have been characterized by using complementary spectroscopic and microscopic techniques including solid-state NMR spectroscopy. The uracil-functionalized SWCNTs are able to self-assemble into regular nanorings with a diameter of 50-70 nm, as observed by AFM and TEM. AFM shows that the rings do not have a consistent height and thickness, which indicates that they may be formed by separate bundles of CNTs. The simplest model for the nanoring formation likely involves two bundles of CNTs interacting with each other via uracil-uracil base-pairing at both CNT ends. These nanorings can be envisaged for the development of advanced electronic circuits.