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. 2019 Feb 5;9(8):4499-4506.
doi: 10.1039/c8ra09998g. eCollection 2019 Jan 30.

Synthesis and physico-chemical properties of a H-cardanol triazole zinc porphyrin conjugate

H Surya Prakash Rao  1   2 , M Kamalraj  1 , M Prabakaran  1
Affiliations

Synthesis and physico-chemical properties of a H-cardanol triazole zinc porphyrin conjugate

H Surya Prakash Rao et al. RSC Adv. .

Abstract

Although a large number of natural and non-natural metalloporphyrins are known, examples with fluorescence and fat-soluble properties are rare. We have achieved the synthesis of a fluorescent and fat-soluble zinc porphyrin incorporating four units of hydrogenated cardanol (H-cardanol). The synthesis is sustainable since the product is derived from cashew-nut shell liquid (CNSL), which is a renewable and bio-waste material. The H-cardanol triazole zinc porphyrin conjugate (HTZPC) was synthesized through applying a copper(i) catalyzed azide-alkyne cycloaddition (CuAAC) reaction between a H-cardanol derived azide and a tetraarylporphyrin derived alkyne. The absorption and emission properties of the hydrocarbon solvent soluble HTZPC were evaluated using UV-vis and fluorescence emission spectra obtained in various solvents. The results were compared with related molecules like a triazole-zinc porphyrin conjugate (TZPC), zinc tetra-C(4)-methoxyphenyl porphyrin (ZP), and a H-cardanol-triazole conjugate (HTC). The results showed that HTZPC undergoes J-type aggregation in both non-polar and highly polar solvents, which is dictated by van der Waals attractive forces between H-cardanol units in polar solvents (e.g. methanol and dimethylformamide) and π-π stacking interactions between porphyrin units in non-polar solvents (hexane). Moreover, the spectra indicated that the triazole units could stabilize the zinc porphyrin via intermolecular coordinate-complex formation. We anticipate that fat-soluble HTZPC could find applications in medical fields (e.g. in the photodynamic therapy of fat tissue).

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Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. Structures of the porphyrin free base 1 (selected numbering and three types of carbons in the porphyrin ring are highlighted), the metallated porphyrin 2, the metallated tetraphenylporphyrin (TPP) 3 and hydrogenated cardanol (H-cardanol) 4.
Fig. 2
Fig. 2. The structure of the H-cardanol-triazole-porphyrin conjugate (HTZPC) 5.
Scheme 1
Scheme 1. The synthesis of the H-cardanol triazole porphyrin conjugate (HTZPC) 5.
Fig. 3
Fig. 3. The structures of the triazole-zinc porphyrin conjugate (TZPC) 6, zinc tetra(4-methoxyphenyl)porphyrin (ZP) 7, and the H-cardanol-triazole conjugate (HTC) 8.
Fig. 4
Fig. 4. UV-vis spectra of HTZPC 5 (black), TZPC 6 (red), ZP 7 (blue), and ZP 7 + HTC 8 (olive) in hexane at room temperature.
Fig. 5
Fig. 5. An ensemble of multiple porphyrin units in HTZPC 5.
Fig. 6
Fig. 6. Absorption spectra of (A) HTZPC 5 (4.19 × 10−4 M), and (B) ZP 7 (1.25 × 10−3 M) in hexane (black), DCM (red), THF (green), EtOAc (blue), MeOH (purple) and DMF (magenta).
Fig. 7
Fig. 7. Emission spectra (excited at 422 nm) of HTZPC 5 (left, 4.19 × 10−4 M) and ZP 7 (right, 1.25 × 10−3 M) soon after the preparation of the solutions (top row) and after two days (bottom row) in hexane (black), DCM (red), THF (green), EtOAc (blue), MeOH (cyan) and DMF (pink).
Fig. 8
Fig. 8. Emission spectra (excited at 422 nm) of HTZPC 5 (4.19 × 10−4 M) in the non-polar solvents hexane (black), CHCl3 (red), petrol (blue), 1-octanol (magenta), toluene (olive blue) and benzene (navy green).
Fig. 9
Fig. 9. Photographs of 5 mg each of HTZPC 5, TZPC 6, ZP 7 and HTC 8 in hexane. While HTZPC 5 and HTC 8 were freely soluble, TZPC 6 and ZP 7 were practically insoluble.
Fig. 10
Fig. 10. Photographs of HTZPC 5 dissolved in six different solvents, namely hexane (Hex), dichloromethane (DCM), tetrahydrofuran (THF), ethyl acetate (EtOAc), methanol (MeOH) and dimethylformamide (DMF).
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References

    1. Milgrom L. R., The Colors of Life: An Introduction to the Chemistry of Porphyrins and Related Compounds, Oxford University Press, Oxford, 1997
    1. Kadish K. M., Porphyrin Science: With Applications to Chemistry, Physics, Materials Science, Engineering, Biology and Medicine, World Scientific, 2010
    1. Ogoshi H. Mizutani T. Acc. Chem. Res. 1998;31:81–89. doi: 10.1021/ar9603165. - DOI
    1. Burrell A. K. Officer D. L. Plieger P. G. Reid D. C. Chem. Rev. 2001;101:2751–2796. doi: 10.1021/cr0000426. - DOI - PubMed
    1. Di Natale C. Martinelli E. Magna G. Mandoj F. Monti D. Nardis S. Stefanelli M. Paolesse R. J. Porphyrins Phthalocyanines. 2017;21:769–781. doi: 10.1142/S1088424617300026. - DOI