En route to the transformation of porphyrin molecules for PDT: Theoretical insights on the reactive oxygen generation of 1D nano-wires and 2D covalent organic frameworks
The application of photosensitizers (PSs) is sometimes limited due to hypoxic environment. To overcome this drawback, one-dimensional infinite tetraphenylporphyrin nano-wires (1D-TPP-WIREs) and two-dimensional tetraphenylporphyrin covalent organic frameworks (2D-TPP-COFs) as Type I photosensitizers (PSs) for photodynamic therapy (PDT) are presented. Meanwhile, the mono-TPP, bis-TPP, and terta-TPP molecules are also studied to investigate the influence of conjugative and metallic effect on the properties of the TPP system. Compared with mono-TPPs, the intra-molecular charge transfer in bis-TPPs and tetra-TPPs is more obvious, the absorption spectra intensity of bis-TPPs and tetra-TPPs is strengthened. Moreover, the 1D-TPP-WIREs and 2D-TPP-COFs with more large conjugated TPP system exhibit photocatalytic activity, which can abstract hydrogen from water to get reactive oxygen OHrad for treatment of hypoxic tumours. Comprehensively consider the properties of charge density distribution, absorption spectra, band edge position of the CB and VB potentials, the 1D-TPP-WIRE-HCu and 2D-TPP-COF-HCu is more suitable for hypoxic Type I PDT.