BODIPY dyes for singlet oxygen and optical limiting applications
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
Optical Limiting Properties of 3, 5-Dithienylenevinylene BODIPY Dyes at 532 nm
- Authors: Harris, Jessica , Gai, Lizhi , Kubheka, Gugu , Mack, John , Nyokong, Tebello , Shen, Zhen
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189274 , vital:44833 , xlink:href="https://doi.org/10.1002/chem.201702503"
- Description: The optical limiting properties of a series of near infrared absorbing 3,5-dithienylenevinylene BODIPY (borondipyrromethene) dyes (1–3) that contain donor and acceptor moieties in their p-conjugation systems were studied by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed when the compounds are embedded into poly(bisphenol carbonate A) polymer thin films, which demonstrates that BODIPY dyes with this type of structure are suitable for use in optical limiting applications.
- Full Text:
- Date Issued: 2017
Photophysical studies of 2, 6-dibrominated BODIPY dyes substituted with 4-benzyloxystyryl substituents
- Authors: Ngoy, Bokolombe Pitchou , Molupe, Nthabeleng , Harris, Jessica , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233068 , vital:50053 , xlink:href="https://doi.org/10.1142/S1088424617500420"
- Description: A series of novel 2,6-dibrominated BODIPY dyes with styryl groups at the 3,5-positions has been prepared, and their photophysical properties have been analyzed to assess their potential utility for use as photosensitizers in photodynamic therapy and in bioimaging.
- Full Text:
- Date Issued: 2017
A chiral hemiporphyrazine derivative
- Authors: Wu, Yanping , Gai, Lizhi , Xiao, Xuqiong , Lu, Hua , Li, Zhifang , Mack, John , Harris, Jessica , Nyokong, Tebello , Shen, Zhen
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240404 , vital:50831 , xlink:href="https://doi.org/10.1002/asia.201600754"
- Description: The synthesis of an optically active hemiporphyrazine with chiral binaphthyl substituents (1) is reported, providing the first example of the incorporation of an intrinsically chiral moiety into the macrocyclic core of a hemiporphyrazine analogue. A negative circular dichroism (CD) signal is observed in the 325–450 nm region of the CD spectrum of (S,S)-1, while mainly positive bands are observed in the 220–325 nm region. Mirror symmetry is observed across the entire wavelength range of the CD spectra of (R,R)-1 and (S,S)-1. An irreversible one-electron oxidation wave with an onset potential at 1.07 V is observed by cyclic voltammetry, along with a reversible one-electron reduction wave at −0.85 V. Density functional calculations reproduce the experimentally observed data and trends, and provide further insight into the nature of the electronic transitions.
- Full Text:
- Date Issued: 2016
Spectroscopic investigations and theoretical calculations of DABCO induced xanthene bridged self-assembled zinc (II) porphyrin dimer
- Authors: Xu, Li , Huang, Tingting , Liang, Xu , Mack, John , Harris, Jessica , Nyokong, Tebello , Li, Minzhi , Zhu, Weihua
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240732 , vital:50866 , xlink:href="https://doi.org/10.1142/S1088424616500231"
- Description: An in-depth study of the electronic structure of a 1,4-diazabicyclo[2.2.2]octane (DABCO) induced molecular self-assembled xanthene-bridged and amide-bonded porphyrin dimer is reported. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are used to identify trends in the optical spectroscopic properties. B3LYP geometry optimization predicts the formation of an almost perfectly eclipsed structure with respect to the two porphyrin rings with the analogous pyrrole nitrogens separated by 7.7–8.1 Å. The observed distinctive derivative-shaped band morphology of the pseudo-Faraday-A11 terms in the MCD spectra has been used to identify the main electronic Q and B-bands and to validate the TD-DFT calculations. The absence of a discernible splitting of the redox steps or a quenching of the fluorescence demonstrates that there is no significant exciton coupling between the two porphyrin rings.
- Full Text:
- Date Issued: 2016