Photophysics, Dynamics, and Energy Transfer in Rigid Mimics of GFP-based Systems

Abstract

Engineering of novel systems capable of efficient energy capture and transfer in a predesigned pathway could potentially boost applications varying from organic photovoltaics to catalytic platforms and have implications for energy sustainability and green chemistry. While light-harvesting properties of different materials have been studied for decades, recently, there has been great progress in the understanding and modeling of short- and long-range energy transfer processes through utilization of metal-organic frameworks (MOFs). In this Forum Article, the recent advances in efficient multiple-chromophore coupling in well-defined metal-organic materials through mimicking a protein system possessing near 100% energy transfer are discussed. Utilization of a MOF as an efficient replica of a protein β-barrel to maintain chromophore emission was also demonstrated. Furthermore, we established a novel dependence of a photophysical response on an electronic configuration for chromophores with the benzylidene imidazolinone core. For that, we prepared 16 chromophores, in which the benzylidene imidazolinone core was modified with electron-donating and electron-withdrawing substituents. To establish the structure-dependent photophysical properties of the prepared chromophores, 11 novel molecular structures were determined by single-crystal X-ray diffraction. These findings allow one to predict the chromophore emission profile inside a rigid framework as a function of the substituent, a key parameter for achieving the spectral overlap necessary to study and increase resonance energy transfer efficiency in MOF-based materials.

ortho and para chromophores of green fluorescent protein: controlling electron emission and internal conversion

“… 21 , 22 , 42 Similar restrictions to torsional motions are also responsible for the enhanced fluorescence yield of chromophores locked inside rigid scaffolds. 10 – 13 …”

“… 6 , 7 The isolated chromophore is virtually non-fluorescent in solution 8 and in vacuo , 9 but can become fluorescent when incorporated in rigid scaffolds such as metal–organic frameworks or other non-native protein environments. 10 – 13 The lack of fluorescence from the free chromophores is widely accepted to be due to ultrafast isomerisation around the C 2 –C 3 –C 4 bridge ( Fig. 1 ) followed by efficient internal conversion taking excited state population back to the electronic ground state.…”

Anion photoelectron spectroscopy of protein chromophores

“…Furthermore, the isolated chromophore is virtually non-fluorescent at biological temperatures in solution [69] and in vacuo [70], but it fluoresces strongly in solution when cooled to 77 K [69] and it has been found to have a sufficiently long excited state lifetime in the gas phase when cooled to 100 K that fluorescence may occur in vacuo at low temperatures [71]. The isolated chromophore can also become fluorescent when incorporated in rigid scaffolds, such as metal-organic frameworks or other non-native protein environments [72][73][74][75]. The lack of fluorescence from the free chromophore at biological temperatures is attributed to ultrafast isomerisation around the central C-C-C bridge linking the phenolate and imidazolinone moieties ( Fig.…”

Red‐Shifted Substrates for FAST Fluorogen‐Activating Protein Based on the GFP‐Like Chromophores

“…[9] Most chromophores are non-fluorescent in solution due to the mobility of their benzylidene fragment which can dissipate their excited-state energy. [10] However, they becomeh ighly emissive when the flexible substituenti s fixed by an externali nfluence [11] or by an internal lock. [12] Previously they weres uccessfully used as fluorogens for various proteins, [13] nucleic acids, [14] and whole cell organelles.…”