R. Majumdar et al.

Porous silsesquioxane cage/porphyrin nanocomposite has been designed as dual fluorescent probe for
sensing and adsorption of heavy metal ions and anions. The hybrid fluorescent probe (TPPSQ) has been
synthesized via cross-linked polymerization between octavinylsilsesquioxane (SQ) and 5,10,15,20-
tetrakis-(4-bromophenyl)porphyrin (TPP). Solid state 29Si and 13C MAS-NMR, FTIR and Energy Dispersive
X-ray (EDX) analysis confirmed the successful incorporation of TPP unit within SQ based network. The BET
analysis and TGA analysis of the fluorescent nanocomposite revealed that the material possesses excellent
thermal stability and high surface area in the range of 433 m²·g-1 along with bimodal micropores centered
at 0.64 nm and 1.26 nm and mesopores centered at 2-3 nm. Incorporation of TPP unit into the polymeric
network make the TPPSQ polymer fluorescent (lex = 420 nm, lem = 650 nm) in different media which is
crucial for chemosensing application. Formation of excimers of TPP units within the polymeric network
of TPPSQ play a pivotal role for selective anion sensing whereas interaction capability of freebase TPP unit
with metal ions play the crucial role for cation sensing. In addition of F- ion, TPPSQ has shown F- induced
‘turn-on’ detection due to interaction between SQ cage and Fion and transformation of TPP excimers to
monomers. On the other hand, after addition of Hg2+ ion, TPPSQ have shown instant ‘turn-off’ detection
because after the binding of TPP unit with Hg2+ ion within the polymeric network, the material chose a
non-radiative relaxation pathway from excited to the ground state.

“Porous silsesquioxane cage and porphyrin nanocomposites: sensing and adsorption for heavy metals and
anions”; Majumdar, R.; Wannasiri, C.; Sukwattanasinitt, M.; Ervithayasuporn, V.* Polym. Chem. 12 (2021),
Symmetry driven: the synthesis of co-substituent octasilsesquioxanes