The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

Kinetics of the Single-Crystal to Single-Crystal Two-Photon Photodimerization of α-<i>trans</i>-Cinnamic Acid to α-Truxillic Acid

The quadratic dependence of the rate of photodimerization of α-trans-cinnamic acid induced by 532 nm pulsed laser light confirms a two-photon mechanism in the single crystals. Single crystals in well-defined orientations and circularly polarized light were used in the experiments. The reaction rate deviates from first-order kinetics, but fits the JMAK expression with a coefficient indicating a mechanism intermediate between a random distribution of product molecules in the crystal and the existence of growing nuclei. The reaction is accompanied by a large change in the monoclinic β-angle of the unit cell, corresponding to increased π-overlap between adjacent molecules and therefore to an increased reaction rate. The improved penetration of the light in the crystal and more homogeneous product formation are significant advantages in studies of mechanisms of chemical reactions in single crystals

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles

The Crystalline Nanocluster Phase as a Medium for Structural and Spectroscopic Studies of Light Absorption of Photosensitizer Dyes on Semiconductor Surfaces

The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to ∼2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti−O distances than observed in the known TiO2 phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti17 cluster are in good agreement with the theoretical values and show a blue shift of ∼0.22 eV relative to those reported for anatase nanoparticles