Abstract
An overview of the solvent-driven aggregation of a series of chiral porphyrin derivatives studied by optical methods (UV/Vis, fluorescence, CD and RLS spectroscopies) is herein reported. The investigated porphyrins are characterized by the presence in the meso-positions of glycol-, steroidal- and glucosteroidal moieties, conferring amphiphilicity and solubility in aqueous media to the primarily hydrophobic porphyrin platform. Aggregation of the macrocycles is driven by a change in bulk solvent composition, forming architectures with supramolecular chirality, steered by the stereogenic centers on the porphyrin peripheral positions. The aggregation behavior and chiroptical properties of the final aggregated species strongly depend on the number and stereogenicity of the ancillary groups that dictate the mutual spatial arrangement of the porphyrin chromophores and their further organization in larger structures, usually detectable by different microscopies, such as AFM and SEM. Kinetic studies are fundamental to understand the aggregation mechanism, which is frequently found to be dependent on the substrate concentration. Additionally, Molecular Mechanics calculations can give insights into the intimate nature of the driving forces governing the self-assembly process. The critical use of these combined methods can shed light on the overall self-assembly process of chirally-functionalized macrocycles, with important implications on the development of chiral porphyrin-based materials.
Highlights
Porphyrins are among the most versatile macrocycles fulfilling vital functions in living systems as well as practical applications including materials science, sensing, photovoltaics or medical treatments [1,2,3,4]
The literature has an abundance of examples that use both approaches to constructing chiral porphyrin assemblies, which, taken together, evidence the complexity and the variety of experimental factors determining the supramolecular chirality of the final systems both in solution [11] and in the solid state [30]
We have focused on the possibility to build up chiral porphyrin suprastructures by assembling inherently chiral porphyrin derivatives having single or multiple stereogenic centers peripherally located on the macrocycle thanks to the conjugation with diverse biomolecules, as amino acids, glucosides or steroids [31,32,33,34,35,36,37,38,39,40,41,42]
Summary
Porphyrins are among the most versatile macrocycles fulfilling vital functions in living systems as well as practical applications including materials science, sensing, photovoltaics or medical treatments [1,2,3,4]. Chiral porphyrin-based architectures can be obtained from either chiral or achiral platforms [11,15,16,17] If in the former case the stereochemical course of the self-assembly process is dictated by the chiral functionalities anchored on the periphery of the macrocycle [18,19], in the other, the interaction of achiral monomers with chiral external effectors, such as hydrodynamic directional forces [20,21], magnetic fields [22], or chiral molecular templates [23,24,25,26,27,28,29] drives the formation of specific suprastructures with chiroptical properties. The self-assembly process is driven by the stereogenic groups that dictate the supramolecular chiral features of the formed non-covalent architectures In this contribution, we report the comprehensive results we gained in the last decade by investigating the solvent-promoted aggregation of porphyrin functionalized with a robust C-glycosidic group, a steroid or glucosylated steroid moieties, respectively. The formation of the aggregated species in aqueous solvent mixtures was studied by spectroscopic, morphological and mechanistic point of view, revealing interesting connections between the type of stereogenic information borne by the porphyrin macrocycle and the resulting aggregates with specific alignment and supramolecular chirality
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
