Self-aggregation of synthetic bacteriochlorophyll- d analogs with a heptaisobutylated pentacyclooctasiloxane (POSS) moiety in single-alkane solvents

Novel bacteriochlorophyll-d analogs bearing a highly hydrophobic Polyhedral Oligomeric SilSesquioxane (POSS) unit linked by an ester or an amide bond on the 17-position were synthesized, and their chlorosomal self-aggregation behavior was demonstrated in single-alkane solvents. Both derivatives formed J-aggregates after refluxing in neat n-decane, similar to those obtained in tetrahydrofuran–n-hexane mixed-solvent systems. Temperature-dependent measurements revealed superior thermal stability for the amide-type analog, highlighting the crucial role of the 17-substituent design in controlling chlorosomal self-aggregation.