Synthesis of porphyrin-phthalocyanine triple-decker arrays around a triphenylene core

Alhunayhin, Sultanah Mohammed N (2024) Synthesis of porphyrin-phthalocyanine triple-decker arrays around a triphenylene core. Doctoral thesis, University of East Anglia.

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Controlling the assembly of multiply functional components is important for both development of fundamental supramolecular chemistry and in the application of complex materials. Double and triple-decker complexes of the porphyrinoid macrocycles display electronic absorption across the whole visible range and into the near IR. When the linking metal(s) are lanthanides, some examples offer further potential as molecular magnets and therefore as high-density information storage components of the future. This project focuses on synthetic strategies to assemble examples of such structures, particularly the synthesis and assembly of new multi-decker systems of porphyrins and phthalocyanines and controlling the synthesis of high-order macrocycle–lanthanide complexes. The chosen core in this project was a triphenylene molecule, where our lab has much experience in producing triphenylenes due to its use as a liquid crystal.

The synthesis of isomeric di-substituted triphenylenes is first described, where link points are introduced at 2,3- and 3,6 positions. Links from these positions to porphyrins through a 5-atom linker then provided the model di-porphyrins with different spacings. The separation between porphyrins was hoped to influence single triple-decker formation when using phthalocyanine as the central core with different ionic radii of lanthanide M3+ salts (La3+ =103pm, Pr3+ =99 pm, Nd3+ =98 pm, Sm3+ =96 pm, Eu3+ =95 pm, Dy3+ =90 pm). The synthesis and investigation the two series of novel single triple-deckers is reported. They have comparable spectroscopic properties and no apparent difference in stability between two distinct isomeric TD complexes was noted. As expected, stable triple deckers were not formed when the small Dy ions were employed.

The selectivity of single triple-decker formation was investigated for 2,3 versus 3,6–bis (porphyrin)triphenylene triple-deckers through competition experiments. No selectivity was observed in competition experiments with different La metals in either model. However, the competition experiment using the two isomeric model di-porphyrins demonstrated significant kinetic selectivity, and in this case the 3,6-isomer was preferentially formed. This result indicated that the corresponding hexa-porphyrin based on fully (beta) substituted triphenylene would selectively form a single-isomer tris triple-decker system. The hexa-porphyrin was successfully constructed and subjected to triple-decker assembly. New TD complexes formed it is observed that the insertion of the final metal ion is difficult and slow, indicating significant congestion in the final complex. The reaction is further complicated by competitive formation if a structure presumed to be a bis-TD, and separation of the reaction components could not be achieved. Finally, the synthesis of alternative bis-TD structures was investigated.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Zoe White
Date Deposited: 27 Jun 2024 13:40
Last Modified: 27 Jun 2024 13:40


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