The effect of hydrogen bonds on the ultrafast relaxation dynamics of a BODIPY dimer

Abstract

The influence of hydrogen bonds (H-bonds) in the structure, dynamics, and functionality of biological and artificial complex systems is the subject of intense investigation. In this broad context, particular attention has recently been focused on the ultrafast H-bond dependent dynamical properties in the electronic excited state because of their potentially dramatic consequences on the mechanism, dynamics, and efficiency of photochemical reactions and photophysical processes of crucial importance for life and technology. Excited-state H-bond dynamics generally occur on ultrafast time scales of hundreds of femtoseconds or less, making the characterization of associated mechanisms particularly challenging with conventional time-resolved techniques. Here, 2D electronic spectroscopy is exploited to shed light on this still largely unexplored dynamic mechanism. An H-bonded molecular dimer prepared by self-assembly of two boron-dipyrromethene dyes has been specifically designed and synthesized for this aim. The obtained results confirm that upon formation of H-bonds and the dimer, a new ultrafast relaxation channel is activated in the ultrafast dynamics, mediated by the vibrational motions of the hydrogen donor and acceptor groups. This relaxation channel also involves, beyond intra-molecular relaxations, an inter-molecular transfer process. This is particularly significant considering the long distance between the centers of mass of the two molecules. These findings suggest that the design of H-bonded structures is a particularly powerful tool to drive the ultrafast dynamics in complex materials.

2D Electronic Spectroscopic Techniques for Quantum Technology Applications

“…Inspired by that, several artificial biomimetic multichromophore systems have been proposed, where the photoactive chromophores were embedded into “structured environments” by covalent linking or by supramolecular self-assembly techniques. Examples of this approach are dimers of interacting chromophores mounted on DNA strands, , chromophores covalently attached to polymeric chains, self-assembled aggregates of dye-functionalized short amino acid sequences, porphyrin nanorings and J-aggregates, , and H-bonded dimers …”

5-(2,6-Diacetamidopyridin-4-yl)-kryptoBODIPY

“…In 2 the modification of the substituents on the chromophoric core increases the electron density towards the center which alters the electron distribution capacity. This flexible approach could open the way for accessing to a plethora of programmable dyes and enables a systematic study of the principal factors affecting the dynamics of the energy migration and possibly driving energy transfer mechanisms, as previously reported [10].…”

“…The compound shows a broad absorption band at 528 nm and a weak emission at around 544 nm (Figure ESI), this latter does not allow to make fluorescence lifetime measurement. The design of DAAP-KBD 2 is in continuation to our recent studies [10]. The ability to form supramolecular dimers of a similar DAAP-BODIPY with complementary uracil BOD-IPY [11] was investigated.…”

3-(3-Hydroxypropyl)-2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxaldehyde Methyl Hemiacetal

“…This work offers a new and convenient procedure for the synthesis of useful scaffolds, which can be employed as starting building blocks for the synthesis of many functional molecules as chromophores (e.g., porphyrins, BODIPY) aimed to obtain functional materials for a wide range of applications [16][17][18].…”