Nakamura, Naoki published the artcileThe response characteristic of optical carbon dioxide sensor using pH indicator immobilized in ethyl cellulose film, Computed Properties of 596-01-0, the publication is Transactions of the Materials Research Society of Japan (2004), 29(3), 923-926, database is CAplus.
A new optical CO2 sensor based on the overlay of the CO2 induced absorbance change of pH indicator α-naphtholphthalein with fluorescence of tetraphenylporphine (TPP) was developed and its CO2 sensing characteristics were studied. The observed fluorescence intensity from TPP at 655 nm increased with increasing CO2 concentration The I100/I0 value that shows the sensitivity of sensor containing 13.4 mmol dm-3 α-naphtholphthalein concentration is estimated to be 168, where I0 and I100 represent observed fluorescence intensities from a film exposed to argon and CO2 saturated condition, resp. The response time of the sensing film containing 13.4 mmol dm-3 α-naphtholphthalein concentration was 3.8 s for switching from argon to CO2 and the recovery time of the sensing film also was 6.8 s for switching from CO2 to argon.
Transactions of the Materials Research Society of Japan published new progress about 596-01-0. 596-01-0 belongs to benzofurans, auxiliary class Benzofuran,Naphthalene,Alcohol,Ester, name is 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, and the molecular formula is C28H18O4, Computed Properties of 596-01-0.
Referemce:
https://en.wikipedia.org/wiki/Benzofuran,
Benzofuran | C8H6O – PubChem