The present invention provides the methods of synthesis of [5]helicene compounds and the use of the said compounds conjugating with biomolecules to work as molecular reporter for diagnostic. The compounds in the present invention have the chemical structure illustrated in the formula (1): wherein G is a connecting group composes of 2 carbon atoms selected from the group consisting of ethane and ethylene; A is a separated or connected group selected from the group consisting of cyano and imide; D1 is selected from the group consisting of oxyalkanoic acid, oxyalkanal and oxyalkanesulfonate; and D2 has structure selected from the group consisting of hydroxyl, oxyalkanoic acid, oxyalkanal, alkyl oxyalkanoate, oxyalkanol and oxyalkanesulfonate. The compounds in the present invention compose of aromatic [5]helicene core comprising long it-conjugating system. The said compounds contain functional groups which able to link with biomolecules and they are soluble in water or other solvents that used in binding process with biomolecules. Moreover, owing to having proper chemical structure, the compounds in the present invention exhibit good fluorescent emission in wavelength of 425-675 nm. When the said compounds connected with biomolecules, the biomolecules give good fluorescence and can be detected under ultraviolet radiation.