Photochromic Pt(II)-M(I) heterotrinuclear complexes, preparation method therefor and use thereof

A Pt2M heterotrinuclear metal-organic alkynyl complex of formula (I):

• [Pt2M(μ-PR2CH2PRCH2PR2)2(C≡CR′)2(C≡CR″)2]+mAm− (I)
• wherein, μ represents bridging;
• PR2CH2PRCH2PR2 is a tridentate phosphine ligand;
• the subscript number of each letter indicates the number of each group;
• M is Au(I), Ag(I), or Cu(I);
• R, R′, and R″ are identical or different, independently selected from alkyl, alkenyl, alkynyl, aryl, and heteroaryl, which are unsubstituted or optionally substituted by one, two, or more R1;
• R1 is selected from alkyl, alkenyl, alkynyl, aryl, halogen (F, Cl, Br, I), trihalomethyl (—CX3, X═F, Cl, Br), —NO2, —CN, —OR3, —N(R4)2, —CO—R5, —SO3H, —S(═O)2R6, —S(═O)R6, —P(═O)(R7)2, tertiary amine cation (—N(R8)3+), and N-substituted pyridyl cation [—C5H4N(R9)+], which are unsubstituted or optionally substituted by one, two, or more R2;
• R2 is selected from alkyl, alkenyl, alkynyl, aryl, halogen (F, Cl, Br, I), trihalomethyl (—CX3, X═F, Cl, Br), —NO2, —CN, —OR3, —N(R4)2, —CO—R5, —SO3H, —S(═O)2R6, —S(═O)R6, —P(═O)(R7)2, tertiary amine cation (—N(R8)3+), and N-substituted pyridyl cation [—C5H4N(R9)+];
• R3 is alkyl, aryl, or heteroaryl;
• R4 is identical or different, independently selected from H, alkyl, aryl, and heteroaryl;
• R5 is H, —OH, alkyl, aryl, or heteroaryl;
• R6, R7, R8, and R9 are independently alkyl, aryl, or heteroaryl;
• and
• Am− is a monovalent or bivalent anion, and m is 1 or 2, and said anion is ClO4−, PF6−, SbF6−, BF4−, B(C6H5)4−, CF3SO3−, or SiF62−.