Fluorescence compounds and preparation method thereof

A fluorescent compound represented by the following [Chemical Formula 1]:

• wherein X and Y are the same or different, and each is independently selected from H, —SO3− and —SO3H;
• R1 and R2 are the same or different, and each is selected from C1-7 alkyl, C8-18 alkyl, —(CH2)mSO3−, —(CH2)mSO3H, and
• R3 and R4 are the same or different, and each is selected from C1-7 alkyl, —(CH2)m′COOZ1 and
• with the proviso that both of R3 and R4 cannot represent any one selected from —(CH2)m′COOZ1 and
• at the same time;
• Z1 and Z2 are the same or different, and each is independently substituted with a substituent selected from H, N-succinimidyl, hydrazinyl, N-hydroxysuccinimidyl, N-hydrosuccinimidyloxy, sulfosuccinimidyloxy, 4-sulfo-2,3,4,5-tetrafluorophenyl, maleinimideC0-10alkylaminyl, vinylsulfonyl, vinylsulfonylC0-6alkylaminyl and aminoC0-6alkyl;
• n is an integer of 1-6;
• m is an integer of 1-7;
• p is an integer of 1-10;
• q is an integer of 0-6;
• r is an integer of 1-10;
• m′ is an integer of 1-7;
• p′ is an integer of 1-10;
• q′ is an integer of 1-10;
• and
• r′ is an integer of 1-10;
• wherein at least one of R1 and R2 is
• or each of R3 and R4 is