Rational design of isostructural 2D porphyrin-based covalent organic frameworks for tunable photocatalytic hydrogen evolution.

Covalent organic frameworks have recently gained increasing attention in photocatalytic hydrogen generation from water. However, their structure-property-activity relationship, which should be beneficial for the structural design, is still far-away explored. Herein, we report the designed synthesis of four isostructural porphyrinic two-dimensional covalent organic frameworks (MPor-DETH-COF, M = H, Co, Ni, Zn) and their photocatalytic activity in hydrogen generation.

Three-Dimensional Covalent Organic Frameworks: From Topology Design to Applications.

ConspectusCovalent organic frameworks (COFs) represent a novel type of crystalline porous polymers with potential applications in many areas. Considering their covalent connectivity in different dimensions, COFs are classified as two-dimensional (2D) layered structures or three-dimensional (3D) networks. In particular, 3D COFs have gained increasing attention recently because of their remarkably large surface areas (>5000 m/g), hierarchical nanopores and numerous open sites.

Self-Assembled Extended π-Systems for Sensing and Security Applications.

Molecules and materials derived from self-assembled extended π-systems have strong and reversible optical properties, which can be modulated with external stimuli such as temperature, mechanical stress, ions, the polarity of the medium, and so on. In many cases, absorption and emission responses of self-assembled supramolecular π-systems are manifested several times higher when compared with the individual molecular building blocks. These properties of molecular assemblies encourage scientists to have a deeper understanding of their design to explore them for suitable optoelectronic applications.

Supramolecular Surface Charge Regulation in Ionic Covalent Organic Nanosheets: Reversible Exfoliation and Controlled Bacterial Growth.

Poor control on the exfoliation of covalent organic frameworks (COFs) remains a disadvantage for their application as two-dimensional nanosheets. An equally important problem is the reversible control at the available surface charges on COFs. Herein, a strategy for the reversible exfoliation, re-stacking, and surface-charge control of a propidium iodide based ionic covalent organic framework, PI-TFP, using cucurbit[7]uril (CB[7]) induced molecular recognition, is reported.

Bimodal detection of carbon dioxide using fluorescent molecular aggregates.

Cyano-substituted p-phenylenevinylene (R-1) aggregates exhibiting fluorescence and Raman spectroscopic responses towards CO2 are described. The aggregation-induced emission (AIE) as well as the aggregation-enhanced Raman scattering (AERS) of R-1 in aqueous conditions was reduced in the presence of a small amount of CO2, which enabled its easy and fast bimodal detection in different analytical samples.

Supramolecular Reassembly of Self-Exfoliated Ionic Covalent Organic Nanosheets for Label-Free Detection of Double-Stranded DNA.

Ionic covalent organic nanosheets (iCONs), a member of the two-dimensional (2D) nanomaterials family, offer a unique functional platform for a wide range of applications. Herein, we explore the potential of an ethidium bromide (EB)-based covalent organic framework (EB-TFP) that self-exfoliates in water resulting in 2D ionic covalent organic nanosheets (EB-TFP-iCONs) for the selective detection of double-stranded DNA (dsDNA). In an aqueous medium, the self-exfoliated EB-TFP-iCONs reassemble in the presence of dsDNA resulting in hybrid EB-TFP-iCONs-DNA crystalline nanosheets with enhanced fluorescence at 600 nm.