The free 7-OH was confirmed by a bathochromic shift upon addition of NaOAc compared to MeOH spectrum (ca 11 nm).
The UV data was as compound I except upon addition of NaOAc, compound IV had a bathochromic shift (275 nm) compared with MeOH spectrum (267 nm) indicative to the presence of free 7-OH.
In the case when both the ground state and the excited state of a molecule are nonpolar, a bathochromic shift is generally observed for the corresponding absorption band upon going from a less polarizable solvent to a more polarizable one [14-17].
Indeed, in all mixtures but one there was a bathochromic shift upon going from a less polarizable mixture to a more polarizable mixture.
This may be due to the bathochromic
absorbance shift of the benzotriazole versus the other two classes of compounds.
For 15 years, we have determined urinary vanillylmandelic acid (VMA) by a method  that relies on the reaction of extracted VMA with the diazo derivative of p-nitroaniline to give a pink chromophore; the chromophore undergoes a bathochromic
shift in the presence of an aprotic solvent and a base to give a blue derivative with maximum absorbance at 600 nm.
Whereas polymers in the film state emit green light with a bathochromic
shift of about 33 and 74 nm in the emission maxima, respectively for PDTOFV and PDTOCN as compared to those of their solution state.
max]) of PCzBT shows a bathochromic
shift of 21 nm compared to that PFBT but having almost the same [pi]--[pi] * character.
shift with increase in curing temperature has been reported in polyimide previously (14).
This is presumably due to the electron delocalization of the chromophoric group resulted from grafting benzophenone chromophoric group to the main polymer chains, and so the extended chromophoric conjugation contributed to bathochromic
and hyperchromic shifts in UV-VIS absorption .
This specific interaction of the dopant with the host polymer influences the PAs properties and the following changes were observed: (i) bathochromic shift of photoluminescence (PL) emission band in DMA solution, (ii) blue shift of absorption bands in DMA solution, (iii) hypsochromic or bathochromic shift of PL emission band in m-cresol solution, (iv) blue shift of absorption bands in MC solution, (v) solubilization of the polymers in organic solvent, by protonation of the polymers.
A systematic bathochromic shift in the position of both bands is observed if DMA is replaced by m-cresol (MC) as the solvent (see Table 1).