Structural Modification and Photochromic Study of Naphthopyran Compounds

摘要

The substituted naphthopyran compounds were prepared via cyclization of substituted 2-naphthnol with 1,1-diaryprop-2-yn-1-ol. The structure-function relationship of the closed and open form of NP-Y was studied by the AM1 method in the Hyperchem package. In the closed form, the backbone of the naphthopyran kept its planarity and two benzene rings were repelled to the two sides by each other. In pyran ring, the bond length of O(1)-C(3) as 1.455 A was longer than that of O(1)-C(naphtho) as 1.378 A, which indicated that O(1)-C(3) was considered as a single bond rather than a double bond. The angle of O(1)-C(1)-C(2) was as small as 113.02刟 and indicated a strong tension which might  be beneficial to the photochromism. In the open form, the all-trans quinone form was proposed as the start configuration for geometric optimism. The merocyanine part could not keep good planarity with naphtho ring, which was due to the repelling force from the hydrogen in naphtho ring. A weak conjugation was observed  throughout the backbone in the open form of the molecule by simulation of the wave function (HOMO).