Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Clear Antismudge Unimolecular Coatings of Diblock Copolymers on Glass Plates

Two poly­[3-(triisopropyloxysilyl)­propyl methacrylate]-<i>block</i>-poly­[2-(perfluorooctyl)­ethyl methacrylate] (PIPSMA-<i>b</i>-PFOEMA) samples and one poly­(perfluoropropylene oxide)-<i>block</i>-poly-[3-(triisopropyloxysilyl)­propyl methacrylate] (PFPO-<i>b</i>-PIPSMA) sample were synthesized, characterized, and used to coat glass plates. These coatings were formed by evaporating a dilute polymer solution containing HCl, which catalyzed PIPSMA’s sol–gel chemistry. Polymer usage was minimized by targeting at diblock copolymer unimolecular (brush) layers that consisted of a sol–gelled grafted PIPSMA layer and an oil- and water-repellant fluorinated surface layer. Investigated is the effect of varying the catalyst amount, polymer amount, as well as block copolymer type and composition on the structure, morphology, and oil- and water-repellency of the coatings. Under optimized conditions, the prepared coatings were optically clear and resistant to writing by a permanent marker. The marker’s trace was the faintest on PFPO-<i>b</i>-PIPSMA coatings. In addition, the PFPO-<i>b</i>-PIPSMA coatings were far more wear-resistant than the PIPSMA-<i>b</i>-PFOEMA coatings

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates

Spirooxazine to Merooxazine Interconversion in the Presence and Absence of Zinc: Approach to a Bistable Photochemical Switch

A spironaphthoxazine (SO) photoswitch was synthesized, and its photochromic behaviors were investigated. SO underwent reversible ring-opening/closure isomerization between a spirocyclic isomer (closed form) and a merocyanine (MO isomer, open form) upon ultraviolet light irradiation. For the model SO in this work, the thermal equilibrium is substantially shifted toward the spirocyclic isomer even at −30.0 °C. However, addition of zinc, as Zn(ClO4)2, exerted an important effect on the thermal reversion process from the open (MO) to the closed form (SO). Kinetic analysis showed that thermal reversion with zinc is retarded more than 13-fold, significantly improving bistability. Moreover, introduction of zinc to the spirooxazine−merooxazine (SO−MO) system resulted in a new absorption band readily distinguishable from the bands arising from spirooxazine and merooxazine. For the first time, to the best of our knowledge, the microscopic rate constants for: MO photogeneration from SO (k1), thermal reversion of MO to SO (k2), complexation of MO with zinc (k3) and for dissociation of the complex, MO−Zn (k4), as well as for the ionization equilibria of Zn(ClO4)2 have been evaluated. The preferred transoid structures of MO and those of MO−Zn derived from the preferred MO structures are considered. Although the kinetic study does not permit elucidation of the nature of zinc binding to MO to give MO−Zn, nor the precursor isomers of MO, a DFT calculational study in progress should shed light on the structure and relative stability of these essential intermediates