Diphosphonate compound and a method for preparing the same and an application of the same

A compound with formula II:

• R1 is H, OH or halogen;
• R2 is —(CH2)n1—Ar—(CH2)n2— or —(CH2)n3—, n1=1˜10, n2=0˜10, and n3=1˜10;
• if n1, n2 or n3≧1, the (CH2)n1, (CH2)n2 or (CH2)n3 may be substituted by halogen, —CN, —NO2 or —OH;
• Ar is arylene or arylene substituted with C1-C6 alkyl, C1-C6 substituted alkyl, halogen, —CN, —NO2 or —OH;
• R3 is Se or S;
• R4 and R5 are independently selected from the group consisting of hydrogen, halogen, —CN, —NO2, —OH, —OR′, —COOR′, —OCOOR′, —COR′, —CON(R′)2, —OCON(R′)2, —SR, —SO2R, —SO2N(R′)2, an —SOR′ group, C1-C10 alkyl, C1-C10 substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl aryl or substituted aryl, wherein each of R and R′ is independently selected from the group consisting of H, alkyl, aryl, substituted alkyl or substituted alkyl;
• or R4 and R5 constitute 3-7 carbons of cyclo alkane, the cyclo alkane may be substituted by C1-C6 alkyl, C1-C6 substituted alkyl, halogen, —CN, —NO2 or —OH;
• R6, R7, R8 and R9 are independently selected from the group consisting of Hydrogen, halogen, —CN, —NO2, —OH, —OR′, —COOR′, —OCOOR′, —COR′, —CON(R′)2, —OCON(R′)2, —SR, —SO2R, —SO2N(R′)2, an —SOR′ group, alkyl, alkenyl, alkynyl, aryl, substituted alkyl, substituted alkenyl, substituted alkynyl or substituted aryl, wherein each of R and R′ is independently selected from H, alkyl, aryl, substituted alkyl or substituted aryl.