Bazı 2-[5-hidroksi-4-(sübstitüefenilazo)-2H-pirazol-3-ilazo]-indan-1,3-dion türevlerinin sentezi ve özelliklerinin incelenmesi The syntheses of 2-[5-oxso-4-(substituted phenylazo)-2,5-dihydro-2H-pyrazol-3-ylazo]-indan-1,3-diones and investigation of electronic spectra of the compounds