Anion recognition with porphyrin-bottomed tetraurea receptors

Influence of solvent and axial coordination on self-assembly of a heteroditopic porphyrin derivative

A novel heteroditopic porphyrin and its zinc complex with four long aliphatic chains on the same side of the porphyrin ring were synthesized and used for controllable self-assembly. A variety of aggregation morphologies, including nanosheets, nanospheres, films, leaves, trunks, nanorods, and disks, were furnished by using different pyridyl ligands to coordinate with the Zn-porphyrin or selecting different solvents.

Influence of meso-linker attachment on the formation of core···π interactions in urea-functionalized porphyrins

The ability to cover the face of a porphyrin macrocycle selectively is an attractive feature for concepts such as catalysis and anion binding that is reliant on porphyrin core interactions. Herein, we have synthesized a family of mono-urea functionalized porphyrin complexes with intent to investigate their potential to form core···π interactions selectively to one face of the porphyrin macrocycle. By altering the distance between the urea moiety and the porphyrin through direct linkage or introducing a linker group we can control the formation of the core interactions. This is clearly seen in the crystal structure of 1-phenyl-3-(2-([10,15,20-triphenylporphyrinato]zinc(II)-5-yl)phenyl)urea where a unique face capping effect is demonstrated. In the crystal of this complex, there is a hydrogen-bonding network between the urea group and the axial methanol ligand forming head-to-tail aggregates with the Zn–O axis all molecules pointing in one direction.

Preparation of highly crystalline nitrogen-doped carbon dots and their application in sequential fluorescent detection of Fe3+ and ascorbic acid

Carbon dots (CDs) have been a new class of fascinating carbon-based fluorescent nanomaterials. In the present work, new N-doped CDs with highly crystalline graphite structures are prepared from renewable precursors, chitosan and tartaric acid, and are well characterized. The prepared CDs are applied as a biocompatible fluorescent sensor for the sequential detection of Fe³⁺ and AA. Among various transition metal ions, Fe³⁺ can selectively quench the fluorescence of CDs. Upon the further addition of AA, the quenched fluorescence of CDs is then restored as Fe³⁺ is reduced to Fe²⁺ by AA, which can be utilized for the fluorescent determination of AA. A good linear relationship in the range of 0-150 μM of AA concentration is established with a low detection limit of 0.02 µM. Moreover, the practical applications of this fluorescent sensing method in measurement of AA in food samples are successfully realized with satisfactory results.

Controllable hierarchical self-assembly of porphyrin-derived supra-amphiphiles

Control of self-assembly is significant to the preparation of supramolecular materials and illustration of diversities in either natural or artificial systems. Supra-amphiphiles have remarkable advantages in the construction of nanostructures but control of shape and size of supramolecular nanostructures is still a great challenge. Here, we fabricate a series of supra-amphiphiles by utilizing the recognition motifs based on a heteroditopic porphyrin amphiphile and its zinc complex. These porphyrin amphiphiles can bind with a few guests including Cl^-, coronene, C₆₀, 4,4'-bipyridine and 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine, which are further applied to facilitate the controllable self-assembly. Addition of these guests result in the formation of various supra-amphiphiles with well-defined structures, thus induce the generation of different aggregates. A diverse of aggregation morphologies including nanospheres, nanorods, films, spheric micelles, vesicles and macrowires are constructed upon the influence of specific complexation, which highlights the present work with abundant control on the shapes and dimensions of self-assemblies.

Porphyrin cage compounds based on glycoluril – from enzyme mimics to functional molecular machines

This Feature Article gives an overview of the application of glycoluril-based porphyrin cage compounds in host–guest chemistry, allosterically controlled self-assembly, biomimetic catalysis, and polymer encoding.