Facile and Rapid Visualization of Colorless Endocrine Disruptor Bisphenol A by Interfacial Charge‐Transfer Transitions with TiO₂ Nanoparticles

Abstract

Bisphenol A (BPA) is an estrogen‐mimicking endocrine disruptor, which has been widely used in the production of polycarbonates and epoxy resins. Because BPA is a colorless material owing to the wide HOMO‐LUMO gap of ca. 4.3 eV, we cannot discern toxic BPA dissolved in solution with eyes. Here, we report a facile and rapid method for visible‐light sensing of BPA with TiO2 nanoparticles. The chemical adsorption of BPA on anatase TiO2 nanoparticles via the two phenol groups induces interfacial charge‐transfer (ICT) transitions from BPA to TiO2 in the visible region. The ICT transitions give rise to visible‐light absorption up to ca. 600 nm, allowing visible‐light sensing of BPA. This method is also applicable to other phenol‐containing endocrine disruptors. More generally, to our best knowledge, this is the first demonstration for visible‐light sensing of colorless toxic organic compounds based on ICT transitions.

Interfacial Charge-Transfer Transitions between TiO2 Nanoparticles and Benzoic Acid Derivatives

“…The latter feature is capable of efficient photoinduced charge transfer with a quantum yield of unity and much less energy loss of photogenerated charge carriers in contrast to the conventional two-step charge separation mechanism such as dye sensitization comprising light absorption and subsequent interfacial charge transfer. Because of these two unique features, ICTT has recently gained much attention as new visible-light absorption and charge separation mechanisms potentially applicable in photoenergy conversions such as photovoltaic conversion ,− and photocatalytic reactions − and chemical/biological sensing technologies based on direct visualization, ,,− surface enhanced Raman scattering (SERS), − and visible-light circular dichroism of colorless organic molecules . Recently, ICTT has been reported in several kinds of wide band gap oxide semiconductors (TiO 2 , SrTiO 3 , BaTiO 3 , ZnO, SnO 2 , etc.)…”

Interfacial charge-transfer transitions in SnO2 functionalized with benzoic acid derivatives

“…1(a). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Due to these key features, ICTT have recently attracted increasing interest because of their potential applications in solar energy conversions such as photovoltaic conversion 10,17,18 and photocatalysis [19][20][21][22][23][24][25][26][27][28][29] and chemical sensing (direct visualization, 2,3,[30][31][32][33] surface enhanced Raman scattering (SERS), 34,35 and visible-light circular dichroism (CD) 36 ). So far, ICTT has been studied in TiO 2 nanoparticles chemisorbed with various organic compounds (phenol, catechol, benzenedithiol, aromatic carboxylic acids, aromatic amines, etc.…”

Inorganic Control of Interfacial Charge-Transfer Transitions in Catechol-Functionalized Titanium Oxides Using SrTiO3, BaTiO3, and TiO2

“…On the basis of these characteristic features, ICT transitions show new potentiality in the following optical and optoelectric functions. For example, it has been reported that ICT transitions serve as a light absorption mechanism for optical sensing of colorless biomolecules ,− including colorless drug molecules and endocrine-disrupting chemicals and also as a direct electron-injection mechanism for solar energy conversions such as photovoltaics and photocatalysis. − In addition, ICT transitions were recently reported to provide efficient photoluminescence in amine-functionalized Si nanoparticles. − In order to advance these functions, fundamental understanding of ICT transitions and control of the optical properties are required. One of the features of ICT transitions is the flexible controllability of the absorption wavelength range by the combination of organic and inorganic materials.…”