Executive Summary : | The inspiration to create molecules with well-defined confined space stems from their resemblance to biological cavities where various complex reaction and electron transfer process takes place. Among others organic cage molecules based on porphyrinoids are of special interest as they are capable of serving both the aforementioned goal there by mimicking natural process in the laboratory. Therefore search for new porphyrin cages of different size, shapes and functions remains synthetically challenging but intriguing research area. In this direction the bigger version of porphyrins the so called expanded porphyrin has a lot more to offer as they preserve the essence of porphyrins yet have significant alteration in terms of structural, electronic, redox, metal-coordination, linear and non-linear optical features that can be related to its large pi-delocalized structure. However, there is no precedence in literature of existence cage type molecule demonstrating expanded porphyrin as a functional building unit. This project aims to address this issue with the anticipation of creating highly functional next generation of organic cage materials based on porphyrinoids. The attainment of such conjecture lies on several factors including well-planned and skilled synthetic methodology. We wish to achieve this by utilizing annulated expanded porphyrins possessing porphyrin like rigid structure despite having a bigger conjugation pathway. On the other hand like porphyrin they also offer functionalization via meso-positions which exactly full fills the criteria in order to make large but rigid delocalized pi-wall with suitable functional group ready to cyclize to form a dimeric box like architecture. Taken altogether the selected expanded porphyrinoids has to offer number of attractive features such as: a) diverse functionalization b) rigid shape, c) large pi-delocalized wall, d) opportunity for metal coordination, and e) stimuli responsiveness and capable of adopting multiple redox state leading to different aromatic and radical state hence capable of changing cage environment. This could possibly impact the guest encapsulation and release that operates through a aromatic switch. We therefore believe this proposed study will provide thoughtful insights about the effect of expanded porphyrin in extending the geometric diversity of organic cage as well as cage environment and its potential applications thereof. |