Photo-and thermoresponsive N-salicylideneaniline derivatives: solid-state studies and structural aspects
- Hulushe, Siyabonga T, Malan, Frederick P, Hosten, Eric C, Lobb, Kevin A, Khanye, Setshaba D, Watkins, Gareth M
- Authors: Hulushe, Siyabonga T , Malan, Frederick P , Hosten, Eric C , Lobb, Kevin A , Khanye, Setshaba D , Watkins, Gareth M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451137 , vital:75021 , xlink:href="https://pubs.rsc.org/en/content/articlehtml/2022/nj/d1nj03056f"
- Description: N-Salicylideneaniline (SA) and its derivatives are known to possess chromism upon exposure to external stimuli. Herein, we present mechanochemical synthesis of a series of photo-and thermoresponsive SAderivatives and report on solid-state stabilisation of their tautomeric forms either by change in temperature or by photoirradiation. The influence of UV light on proton transfer between the enol-imine (EI) and keto-amine (KA) forms was investigated at l1 = 254 and l2 = 365 nm. Differential scanning calorimetry (DSC) measurements provided extra information on the thermodynamic relationship between the prototropic tautomers, and their exposition to liquid nitrogen, combined with variable temperature single-crystal X-ray diffraction (VT-SCXRD) and spectroscopic data, ascertained structural reasons for the intrinsic thermo-optical properties of the compounds. A series of structural determinations between 150 and 300 K further shed light on the thermomechanical behaviour exhibited by the thermoresponsive compounds. By virtue of calorimetry we were able to demonstrate proton transfer via the intramolecular ON hydrogen bond over the temperature range 193–453 K. This present work demonstrates the importance of applying complementary analytical techniques and appropriate approaches for understanding the switching behaviour between the EI and KA forms. Furthermore, the assertion that it is predominantly the planarity (j o 251) that determines thermochromaticity is questioned.
- Full Text:
- Authors: Hulushe, Siyabonga T , Malan, Frederick P , Hosten, Eric C , Lobb, Kevin A , Khanye, Setshaba D , Watkins, Gareth M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451137 , vital:75021 , xlink:href="https://pubs.rsc.org/en/content/articlehtml/2022/nj/d1nj03056f"
- Description: N-Salicylideneaniline (SA) and its derivatives are known to possess chromism upon exposure to external stimuli. Herein, we present mechanochemical synthesis of a series of photo-and thermoresponsive SAderivatives and report on solid-state stabilisation of their tautomeric forms either by change in temperature or by photoirradiation. The influence of UV light on proton transfer between the enol-imine (EI) and keto-amine (KA) forms was investigated at l1 = 254 and l2 = 365 nm. Differential scanning calorimetry (DSC) measurements provided extra information on the thermodynamic relationship between the prototropic tautomers, and their exposition to liquid nitrogen, combined with variable temperature single-crystal X-ray diffraction (VT-SCXRD) and spectroscopic data, ascertained structural reasons for the intrinsic thermo-optical properties of the compounds. A series of structural determinations between 150 and 300 K further shed light on the thermomechanical behaviour exhibited by the thermoresponsive compounds. By virtue of calorimetry we were able to demonstrate proton transfer via the intramolecular ON hydrogen bond over the temperature range 193–453 K. This present work demonstrates the importance of applying complementary analytical techniques and appropriate approaches for understanding the switching behaviour between the EI and KA forms. Furthermore, the assertion that it is predominantly the planarity (j o 251) that determines thermochromaticity is questioned.
- Full Text:
Reaction of Perrhenate with Phthalocyanine Derivatives in the Presence of Reducing Agents and Rhenium Oxide Nanoparticles in Biomedical Applications
- Ntsimango, Songeziwe, Gandidzanwa, Sendibitiyosi, Joseph, Sinelizwi V, Hosten, Eric C, Randall, Marvin, Edkins, Adrienne L, Khene, Samson M, Mashazi, Philani N, Nyokong, Tebello, Abrahams, Abubak’r, Tshentu, Zenixole R
- Authors: Ntsimango, Songeziwe , Gandidzanwa, Sendibitiyosi , Joseph, Sinelizwi V , Hosten, Eric C , Randall, Marvin , Edkins, Adrienne L , Khene, Samson M , Mashazi, Philani N , Nyokong, Tebello , Abrahams, Abubak’r , Tshentu, Zenixole R
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300257 , vital:57910 , xlink:href="https://doi.org/10.1002/open.202200037"
- Description: A novel alternative route to access rhenium(V)−phthalocyanine complexes through direct metalation of metal-free phthalocyanines (H2Pcs) with a rhenium(VII) salt in the presence of various two-electron reducing agents is presented. Direct ion metalation of tetraamino- or tetranitrophthalocyanine with perrhenate (ReO4−) in the presence of triphenylphosphine led to oxidative decomposition of the H2Pcs, giving their respective phthalonitriles. Conversely, treatment of H2Pcs with ReO4− employing sodium metabisulfite yielded the desired ReVO−Pc complex. Finally, reaction of H2Pcs with ReO4− and NaBH4 as reducing agent led to the formation of rhenium oxide (RexOy) nanoparticles (NPs). The NP synthesis was optimised, and the RexOy NPs were capped with folic acid (FA) conjugated with tetraaminophthalocyanine (TAPc) to enhance their cancer cell targeting ability. The cytotoxicity profile of the resultant RexOy−TAPc−FA NPs was assessed and found to be greater than 80 % viability in four cell lines, namely, MDA−MB-231, HCC7, HCC1806 and HEK293T. Non-cytotoxic concentrations were determined and employed in cancer cell localization studies. The particle size effect on localization of NPs was also investigated using confocal fluorescence and transmission electron microscopy. The smaller NPs (≈10 nm) were found to exhibit stronger fluorescence properties than the ≈50 nm NPs and exhibited better cell localization ability than the ≈50 nm NPs.
- Full Text:
- Authors: Ntsimango, Songeziwe , Gandidzanwa, Sendibitiyosi , Joseph, Sinelizwi V , Hosten, Eric C , Randall, Marvin , Edkins, Adrienne L , Khene, Samson M , Mashazi, Philani N , Nyokong, Tebello , Abrahams, Abubak’r , Tshentu, Zenixole R
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300257 , vital:57910 , xlink:href="https://doi.org/10.1002/open.202200037"
- Description: A novel alternative route to access rhenium(V)−phthalocyanine complexes through direct metalation of metal-free phthalocyanines (H2Pcs) with a rhenium(VII) salt in the presence of various two-electron reducing agents is presented. Direct ion metalation of tetraamino- or tetranitrophthalocyanine with perrhenate (ReO4−) in the presence of triphenylphosphine led to oxidative decomposition of the H2Pcs, giving their respective phthalonitriles. Conversely, treatment of H2Pcs with ReO4− employing sodium metabisulfite yielded the desired ReVO−Pc complex. Finally, reaction of H2Pcs with ReO4− and NaBH4 as reducing agent led to the formation of rhenium oxide (RexOy) nanoparticles (NPs). The NP synthesis was optimised, and the RexOy NPs were capped with folic acid (FA) conjugated with tetraaminophthalocyanine (TAPc) to enhance their cancer cell targeting ability. The cytotoxicity profile of the resultant RexOy−TAPc−FA NPs was assessed and found to be greater than 80 % viability in four cell lines, namely, MDA−MB-231, HCC7, HCC1806 and HEK293T. Non-cytotoxic concentrations were determined and employed in cancer cell localization studies. The particle size effect on localization of NPs was also investigated using confocal fluorescence and transmission electron microscopy. The smaller NPs (≈10 nm) were found to exhibit stronger fluorescence properties than the ≈50 nm NPs and exhibited better cell localization ability than the ≈50 nm NPs.
- Full Text:
- «
- ‹
- 1
- ›
- »