Optical limiting properties, structure and simplified TD-DFT calculations of scandium tetra-15-crown-5 phthalocyaninates:
- May, Aviwe K, Majumdar, Poulomi, Martynov, Alexander G, Lapkina, Lyudmila A, Troyanov, Sergey I, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Mack, John, Nyokong, Tebello
- Authors: May, Aviwe K , Majumdar, Poulomi , Martynov, Alexander G , Lapkina, Lyudmila A , Troyanov, Sergey I , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Mack, John , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163553 , vital:41048 , https://0-doi.org.wam.seals.ac.za/10.1142/S108842462050011X
- Description: The optical limiting properties of crown-ether-substituted scandium(III) phthalocyaninate complexes, bis-tetra-15-crown-5-phthalocyaninates Sc[(15C5)4Pc]∙022•0 (I) and Sc[(15C5)4Pc]−22− (Ia), together with monophthalocyaninate [(15C5)4Pc]Sc(OAc) (II) were measured by using the Z-scan technique (532 nm laser and pulse rate of 10 ns).
- Full Text:
- Date Issued: 2020
- Authors: May, Aviwe K , Majumdar, Poulomi , Martynov, Alexander G , Lapkina, Lyudmila A , Troyanov, Sergey I , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Mack, John , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163553 , vital:41048 , https://0-doi.org.wam.seals.ac.za/10.1142/S108842462050011X
- Description: The optical limiting properties of crown-ether-substituted scandium(III) phthalocyaninate complexes, bis-tetra-15-crown-5-phthalocyaninates Sc[(15C5)4Pc]∙022•0 (I) and Sc[(15C5)4Pc]−22− (Ia), together with monophthalocyaninate [(15C5)4Pc]Sc(OAc) (II) were measured by using the Z-scan technique (532 nm laser and pulse rate of 10 ns).
- Full Text:
- Date Issued: 2020
Methodological Survey of Simplified TD-DFT Methods for Fast and Accurate Interpretation of UV−Vis−NIR Spectra of Phthalocyanines
- Martynov, Alexander G, Mack, John, May, Aviwe K, Nyokong, Tebello, Gorbunova, Yulia G, Tsivadze, Aslan Yu
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
- Date Issued: 2019
- Authors: Martynov, Alexander G , Mack, John , May, Aviwe K , Nyokong, Tebello , Gorbunova, Yulia G , Tsivadze, Aslan Yu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186915 , vital:44547 , xlink:href="https://doi.org/10.1021/acsomega.8b03500"
- Description: A methodological survey of density functional theory (DFT) methods for the prediction of UV−visible (vis)−near-infrared (NIR) spectra of phthalocyanines is reported. Four methods, namely, full time-dependent (TD)-DFT and its Tamm−Dancoff approximation (TDA), together with their simplified modifications (sTD-DFT and sTDA, respectively), were tested by using the examples of unsubstituted and alkoxy-substituted metal-free ligands and zinc complexes. The theoretical results were compared with experimental data derived from UV−visible absorption and magnetic circular dichroism spectroscopy. Seven popular exchange-correlation functionals (BP86, B3LYP, TPSSh, M06, CAM-B3LYP, LC-BLYP, and ωB97X) were tested within these four approaches starting at a relatively modest level using 6-31G(d) basis sets and gas-phase BP86/def2-SVP optimized geometries. A gradual augmentation of the computational levels was used to identify the influence of starting geometry, solvation effects, and basis sets on the results of TD-DFT and sTD-DFT calculations. It was found that although these factors do influence the predicted energies of the vertical excitations, they do not affect the trends predicted in the spectral properties across series of structurally related substituted free bases and metallophthalocyanines. The best accuracy for the gas-phase vertical excitations was observed in the lower-energy Q-band region for calculations that made use of range-separated hybrids for both full and simplified TD-DFT approaches. The CAMB3LYP functional provided particularly accurate results in the context of the sTD-DFT approach. The description of the higherenergy B-band region is considerably less accurate, and this demonstrates the need for further advances in the accuracy of theoretical calculations. Together with a general increase in accuracy, the application of simplified TD-DFT methods affords a 2−3 orders of magnitude speedup of the calculations in comparison to the full TD-DFT approach. It is anticipated that this approach will be widely used on desktop computers during the interpretation of UV−vis−NIR spectra of phthalocyanines and related macrocycles in the years ahead.
- Full Text:
- Date Issued: 2019
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