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

Synthetically modified green fluorescent protein chromophore derivative was prepared, its crystal structure and spectral properties were studied. Crystal data for C 19 H 18 N 2 O 4 : triclinic, space group P -1 (no. 2), a = 8.2506(17) A, b = 11.934(2) A, c = 17.461(4) A, α = 102.89(3)°,   β = 94.62(3)°, γ = 96.68(3)°, V = 1654.5(6) A 3 , Z = 4, T = 173(2) K, μ(MoKα) = 0.096 mm -1 , D calc = 1.358 g/cm 3 , 7227 reflections measured (4.722° ≤ 2Θ ≤ 53.996°), 7227 unique ( R int = 0.0453, R sigma = 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.