TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): The ruthenium complex is synthesized by reacting a heterocyclic tridentate ligand of formula (1a), (RuCl2(p-cymene))2 and N,N-dimethylformamide under nitrogen atmosphere; reacting a ligand (2,2')bipyridinyl-4,4'-dicarboxylic acid (H2-dcbpy) to the mixture under dimethylformamide (DMF) atmosphere; after the reaction, vacuuming the DMF; ultrasonically vibrating the mixture; centrifuging the mixture to get a solid; washing the solid was with acetonitrile, to obtain the ruthenium complex. Preferred Structure: The L1 has a structural formula (IV). The L2 has a structural formula (V). Preferred Definitions:    R1, R2 of L1=H or alkyl, or COOH or its acid radical salt, or carboxylic acid or its acid radical salt;    R3 of L1=alkyl, perfluorinated alkyl, alkoxy, or CF3 (preferably);    X=halogens, halogen ions, halogen cyanide ions, sulfur cyanide ion, sulfite ion, or thiosulfate;    L2=2,2'-bipyridine; and    R4, R5 of L2=carboxylic acid or its acid radical salt, sulfonic acid or its acid radical salt, or phosphoric acid or its acid radical salt.    SPECIFIC COMPOUNDS - 2 Ruthenium complex compounds (I) are specifically disclosed, e.g. compounds (S1) and (S2).    EXAMPLE - A heterocyclic tridentate ligand (1a) and 0.20 g of (RuCl2(p-cymene))2 were added into a reaction bottle. Under the nitrogen atmosphere, N,N-dimethylformamide (15 mL) was added and reacted at 60 degrees C for 4 hours. Then, a ligand (2,2')bipyridinyl-4,4'-dicarboxylic acid (H2-dcbpy) (0.16 g) was added into the reaction bottle, and reacted at 150 degrees C for 4 hours under dimethylformamide (DMF) atmosphere. After the reaction, the DMF was vacuumed, a small amount of DMF (1-2 mL) was added, and then acetonitrile methyl cyanide (CH3CN) (5-7 mL) was added. The mixture was ultrasonic-vibrated for 20 minutes, and centrifuged to get a solid. The solid was washed with acetonitrile, to get 0.2 g of a first-step compound (Ru(bpypz)(H2-dcbpy)Cl) (S1) (46% yield). The ruthenium complex (S1) (0.10 g) and ammonium thiocyanate (NH4NCS) (0.34 g) were added in a reaction bottle, and DMF (15 ml) was added and reacted at 140 degrees C for 5 hours. Next, DMF was vacuumed, and deionized water (5-7 mL) was added. The mixture was centrifuged to get a solid. Then, the solid was washed with CH3CN to get 0.08 g of a second-step ruthenium complex (Ru(bpypzCF3)(H2-dcbpy)NCS) (S2) (77% yield).