Excited-state locked amino analogues of the green fluorescent protein chromophore with a giant Stokes shift

Abstract

We design a new class of excited-state locked GFP chromophores which intrinsically exhibit a very large Stokes shift.

Locking the GFP Fluorophore to Enhance Its Emission Intensity

“…This approach to block the isomerization of benzylidene double bond uses a link between the phenyl ring and the core of the imidazolone. Another approach has been attempted, using a boron complex formed between the carbonyl of the imidazolone and an amino group introduced on the double bond of the benzylidene (chromophores 28 and 29, Figure 27) [45]. The difluoroborate complex efficiently blocks the Z/E isomerization of the double bond and, as expected, the quantum yield increases up to 0.60.…”

Designing Red-Shifted Molecular Emitters Based on the Annulated Locked GFP Chromophore Derivatives

“…Initially, all valence π-type orbitals were included in the active spaces of the analyzed molecules using the state-averaged SA(7)-MCSCF(1+2) method, which was restricted to single and double excitations within an active space with respect to a reference closed-shell configuration. We used the following active spaces: (14,13), i.e., 14 electrons distributed over 13 orbitals, for compound 1, (20,19) for compound 1A, (28,27) for compound 2A, (36,35) for compound 3A, (28,27) for compound 4A, (18,17) for compound 1B, (22,21) for compound 2B, (30,29) for compound 3B, (18,17) for compound 1C, (22,21) for compound 2C, (18,17) for compound 1D, and (22,21) for compound 2D. The active spaces were then reduced for the subsequent complete active space self-consistent field calculations at the SA(7)-CASSCF (14,14) level of theory.…”

“…One way to fix the arylidene fragment is to introduce the difluoroboryl bridge into the chemical structure of BDI chromophores. Indeed, fluorescence is recovered in various locked GFP derivatives [14][15][16][17][18].…”

Fluorescent 2‐Hydroxy‐3‐(pyridin‐2‐yl)‐4H‐quinolizin‐4‐ones through Dimerization of Pyridineacetic Acids

“…This problem can be overcome by their annulation with conjugated systems, which leads to noticeable fluorescence in solutions. [9,10] In particular, derivatives of pyridine containing the enol (or any similar) fragment in the second position have become relatively widespread (Scheme 1). [11,12] These dyes are typically characterized by absorption in the range of 300-400 nm and emission at 400-550 nm with FQYs up to 80 %.…”

“… [6,7] Therefore, these dyes are promising as aggregation‐induced emitters (AIE), [8] and cannot be considered as conventional fluorescent dyes. This problem can be overcome by their annulation with conjugated systems, which leads to noticeable fluorescence in solutions [9,10] . In particular, derivatives of pyridine containing the enol (or any similar) fragment in the second position have become relatively widespread (Scheme 1).…”