Crystal structure and spectral studies of green fluorescent protein (GFP) chromophore analogue ethyl 2-[(4Z)-(6-hydroxy naphthalen-2-yl) methylene)-2-methyl-5-oxo-4,5-di hydro-1H-imidazol-1-yl] acetate

Abstract

Synthetically modified green fluorescent protein chromophore derivative was prepared, its crystal structure and spectral properties were studied. Crystal data for C19H18N2O4: triclinic, space group P-1 (no. 2), a = 8.2506(17) Å, b = 11.934(2) Å, c = 17.461(4) Å, α = 102.89(3)°, β = 94.62(3)°, γ = 96.68(3)°, V = 1654.5(6) Å3, Z = 4, T = 173(2) K, μ(MoKα) = 0.096 mm-1, Dcalc = 1.358 g/cm3, 7227 reflections measured (4.722° ≤ 2Θ ≤ 53.996°), 7227 unique (Rint = 0.0453, Rsigma = 0.0662) which were used in all calculations. The final R1 was 0.0561 (I > 2σ(I)) and wR2 was 0.1658 (all data). The single crystal structure showed, the benzylidine moiety adopts Z-conformation in solid state and the molecules were associated by various O−H···O and C−H···O non-covalent interactions. The UV absorption-emission spectral analysis indicated that a significant red shift of emission observed at alkaline pH indicating its utility for live cell imaging applications.

Polymorphs of Green Fluorescence Protein Chromophore Analogue: Fluorescence Switching with Thermal Stimuli

“…We have been working on the polymorph and multicomponent crystal development of chromophores of green fluorescent protein (GFP) for a broader range of fluorescence emissions. The chromophore of GFP has gained remarkable recognition in recent years due to its excellent photoluminescence properties. , The high fluorescence emission displayed by GFP chromophore in the crystalline state is due to restricted Z -conformation, unlike in solution, which shows internal E – Z isomerization . Previously, we reported the five concomitant polymorphs of the synthetically modified chromophore of green fluorescent protein (GFP), solely due to the interplay of isoenergetic weak intermolecular interactions in molecular aggregation.…”

“…24,25 The high fluorescence emission displayed by GFP chromophore in the crystalline state is due to restricted Z-conformation, unlike in solution, which shows internal E−Z isomerization. 13 Previously, we reported the five concomitant polymorphs of the synthetically modified chromophore of green fluorescent protein (GFP), solely due to the interplay of isoenergetic weak intermolecular interactions in molecular aggregation. The different fluorescence emission in these polymorphs was attributed to the differences in π-stacking interactions.…”

“…Generally, the photophysical properties of chromophores are tuned by a modification to their molecular structures. , However, some chromophores in the solution are weakly emissive due to the conformational flexibility, in particular, the E – Z isomerization of GFP chromophore (Figure S1, SI). However, the supramolecular effect in the solid state restricts the free rotation around the single bond, thus enhancing the luminescence. − Fluorescence due to molecular aggregation in crystals has been reported for various organic systems . Furthermore, the difference in the supramolecular assembly, due to either dissimilar conformation or crystal symmetry, also alters the fluorescent emissions .…”

Five concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with π-stacking interactions

“…However, in the excited state, the internal E/Z isomerization of GFPc (Fig. S1 in the supporting information) makes it weakly emissive in solution (Wu & Burgess, 2008;Puthuvakkal & Manoj, 2019). Naumov et al correlated the photomechanical properties, dimerization and dimorphic modifications of various GFPc crystals with hydrogen bonding and -stacking interactions (Naumov et al, 2010).…”