SYNTHESIS AND CHARACTERIZATION OF PORPHYRINS

[Synthesis and Characterization of Porphyrins for use in nanoparticle capture and assembly

ABSTRACT

Gold nanoparticles stabilized by meso-5,10,15,20-tetrakis_2-thienyl_porphyrin _2T_ via physisorption_2T-AuNP_ were synthesized, and the electronic transport of assemblies of these films was studied. The adsorption mechanism of 2T on gold nanoparticles was examined using UV-vis-NIR, IR, Raman, and 1H-NMR spectroscopy, which showed no evidence of any covalent bonding between 2T and the gold nanoparticles. In temperature-dependent resistivity measurements, a crossover from thermally assisted hopping to Efros Shklovskii-type variable-range hopping _ES-VRH_ was observed around 50 K on decreasing the temperature.

At higher temperatures, the 2T-AuNP assembly structure followed an Arrhenius plot _EA=15 meV_ with ohmic I-V characteristics at each measurement point. On the other hand, the activation energy at lower temperatures decreased nonlinearly in a T-1 plot, and the logarithm of the resistance obeyed a T-1/2 law, corresponding to an ES-VRH mechanism, which is predicted for disordered materials as a variable-range hopping mechanism influenced by strong Coulomb interactions. ES-VRH behavior has been observed previously in saturated molecule/gold nanoparticle assemblies and was confirmed in our 2T-AuNP assembly. Electronically active conjugated molecules were successfully incorporated between the nanoparticles, keeping the electronic structure of the gold nanoparticle and 2T moieties isolated from each other.

ACKNOWLEDGEMENT

I would first like to express my gratitude for my research coordinator, colleagues, and peers and family whose immense and constant support has been a source of continuous guidance and inspiration (Andreasen, 1991).

DECLARATION

I [type your full first names & surname here], declare that the following dissertation/thesis and its entire content has been an individual, unaided effort and has not been submitted or published before. Furthermore, it reflects my opinion and take on the topic and is does not represent the opinion of the University.

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Table of Content

ABSTRACT2

ACKNOWLEDGEMENT3

DECLARATION4

Introduction7

Background of Study9

Purpose of Study10

Significance of Study10

CHAPTER II12

Literature Review12

Synthesis18

Tabel 221

Laboratory synthesis21

Self-Assembly Of Porphyrins21

Chemistry of Porphyrins29

A Utility Player29

A Carrier of Oxygen31

A Cleaner of Foreign Substances32

Chlorophylls and Vitamins33

The Elegant World of Artificial Porphyrins35

Molecules with the Name of Jewels37

CHAPTER III40

Research Methodology40

Materials40

Synthesis of gold nanoparticles41

Self-assembly of porphyrin-based supramolecules41

Preparation of porphyrin-based supramolecule-coated gold nanoparticles41

Measurement42

Experimental I42

Synthesis of 2T-AuNP42

Fabrication and transport properties of the 2T-AuNP assemblies44

CHAPTER IV46

Results and discussion46

Design and self-assembly of porphyrin-based supramolecules46

Optical properties of gold nanoparticles coated with porphyrin-based supramolecules49

TEM images51

Electrochemical properties52

Experimental II53

Characterization of 2T-AuNP54

Adsorption mechanism between 2T and gold nanoparticles54

Fabrication of a 2T-AuNP assembly55

Temperature dependence of the charge transport of a 2T-AuNP assembly structure56

Electron transport mechanism60

CHAPTER V63

Conclusions63

References65

CHAPTER I

Introduction

The synthesis characterization and stability of porphyrin nanoparticles of 20-200 nm diameter presented herein is general for meso arylporphyrins. The elegance of the method lies in its simplicity. This work shows that the agent used to prevent agglomeration can be covalently attached to the dye forming the particle or be part of the solvent system. It also demonstrates that these and other types of dyes with a range of photonic properties do not need to be prepared by inclusion in external matrices or by designed self-assembly a priori. The matrix may severely limit the functionality of the particles in the former case and at present this size of particle ...