Impact of photosensitizer orientation on the distance dependent photocatalytic activity in zinc phthalocyanine–nanoporous gold hybrid systems

Nanoporous gold powder was functionalized in a two-step approach by an azide terminated alkanethiol self-assembled monolayer (SAM) and a zinc(ii) phthalocyanine (ZnPc) derivative by copper catalyzed azide-alkyne cycloaddition (CuAAC). A series of different hybrid systems with systematic variation of the alkyl chain length on both positions, the alkanethiol SAM and the peripheral substituents of the ZnPc derivative, was prepared and studied in the photooxidation of diphenylisobenzofuran (DPBF). An enhancement by nearly one order of magnitude was observed for the photosensitized singlet oxygen (1O2) generation of the hybrid systems compared to the same amount of ZnPc in solution caused by the interaction of the npAu surface plasmon resonance and the excited state of the immobilized sensitizer. This interaction was shown to be distance dependent, with decreasing activity for short SAMs with alkyl chain lengths < 6 methylene groups caused by quenching of the excited state via electron transfer as well as decreasing activity for SAMs with n > 8 methylene groups due to decreasing energy transfer for long distances. An unexpected distance dependent behaviour was observed for the variation of the peripheral alkyl chain on the photosensitizer revealing a planar orientation of the immobilized photosensitizer on the nanoporous gold surface by a penta-coordinated central zinc ion through interaction with free azide groups from the self-assembled monolayer.


Fig. S2:
UV Vis spectra for the photooxidation of DPBF with H2-3 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.4 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S3:
UV Vis spectra for the photooxidation of DPBF with H1-4 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 2.1 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S4:
UV Vis spectra for the photooxidation of DPBF with H2-4 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.8 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S5:
UV Vis spectra for the photooxidation of DPBF with H1-5 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.5 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S6:
UV Vis spectra for the photooxidation of DPBF with H2-5 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.5 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S7:
UV Vis spectra for the photooxidation of DPBF with H1-6 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.5 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S8:
UV Vis spectra for the photooxidation of DPBF with H2-6 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.7 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

Fig. S9:
UV Vis spectra for the photooxidation of DPBF with H1-7 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.6 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-10 Supplementary data for the photooxidation of DPBF with H2-7 using different irradiation wavelengths
Fig. S10: UV Vis spectra for the photooxidation of DPBF with H2-7 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.4 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-11 Supplementary data for the photooxidation of DPBF with H1-8 using different irradiation wavelengths
Fig. S11: UV Vis spectra for the photooxidation of DPBF with H1-8 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.3 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-12 Supplementary data for the photooxidation of DPBF with H2-8 using different irradiation wavelengths
Fig. S12: UV Vis spectra for the photooxidation of DPBF with H2-8 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.2 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-13 Supplementary data for the photooxidation of DPBF with H1-9 using different irradiation wavelengths
Fig. S13: UV Vis spectra for the photooxidation of DPBF with H1-9 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.4 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-14 Supplementary data for the photooxidation of DPBF with H2-9 using different irradiation wavelengths
Fig. S14: UV Vis spectra for the photooxidation of DPBF with H2-9 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.7 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-15 Supplementary data for the photooxidation of DPBF with H1-10 using different irradiation wavelengths
Fig. S15: UV Vis spectra for the photooxidation of DPBF with H1-10 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.4 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-16 Supplementary data for the photooxidation of DPBF with H2-10 using different irradiation wavelengths
Fig. S16: UV Vis spectra for the photooxidation of DPBF with H2-10 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.6 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-17 Supplementary data for the photooxidation of DPBF with H1-11 using different irradiation wavelengths
Fig. S17: UV Vis spectra for the photooxidation of DPBF with H1-11 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.5 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.

ESI-18 Supplementary data for the photooxidation of DPBF with H2-11 using different irradiation wavelengths
Fig. S18: UV Vis spectra for the photooxidation of DPBF with H2-11 as hybrid photocatalyst employing either a 550 nm cut-on filter (a), a 700 nm bandpass filter (b) or a 550 nm bandpass filter (c) for irradiation. The amount of converted DPBF was determined using Labert Beers law and the extinction coefficinet of 23000 L mol -1 at λ = 415 nm. Turnover numbers (TON) were calculated from the amount of converted DPBF and the illuminated photosensitizer amount of 1.7 x 10 -10 mol as determined from ICP-MS. Turnover frequencies (TOF) were obtained by linear regression from the plots of TON vs. reaction time in the linear regime before saturation effects become dominant.