Octacationic and axially di-substituted silicon (IV) phthalocyanines for photodynamic inactivation of bacteria

Axially Decorated SiIV‐phthalocyanines Bearing Mannose‐ or Ammonium‐conjugated Siloxanes: Comparative Bacterial Labeling and Photodynamic Inactivation,

“…Until now, there are relatively few PSs that highly efficiently act against Gram-negative and positive bacteria alike, and the localization of the positive charge plays an important role. New Si IV Pc were recently reported with four and eight positive charges within the periphery of the macrocycle, but they do not reach the phototoxicity against Gramnegative E. coli of the herein described compound 2 (42)(43)(44). We conclude that axial cationic groups constitute an important structural feature to extend the photosensitizing spectrum against Gram-negative bacteria while keeping the activity against Gram-positive cells.…”

Silicon phthalocyanines: synthesis and resurgent applications

“…In order to form a siloxane bond in the axial position, precursor 2 is refluxed with an excess of silanols or monochlorosilanes to obtain 4 (yields ~ 40-70%). 13,16,17,[39][40][41][42] Reactions were usually carried out for short durations ranging from 3-6 h in non-polar solvents (e.g. dichlorobenzene and toluene) in presence of a mild base (e.g.…”

“…14,15 Extensive synthetic methodologies have been developed for preparation of symmetrical and unsymmetrical SiPcs, often containing both tetravalent (axial) and hexavalent (core) silicon in the same structure. 16,17 Remarkably, axial Si-O and Si-C bonds exhibit NIR light induced dissociation rendering novel applications of SiPcs in medicinal biology, beyond the context of photodynamic therapy. [18][19][20][21][22] These unique properties coupled with the inexpensive cost of synthesis and low toxicity have resulted in fascinating applications of SiPcs in major fields of research including cancer phototherapy, NIR imaging, organic photovoltaics, organic electronics and photocatalysis.…”

Gaining Access to Bacteria through (Reversible) Control of Lipophilicity

“…[12] However,cationic character is not the sole determinant fore fficient photoinactivation. [13] For instance,t etra-a nd octa-cationic silicon(IV) phthalocyanines bearing four [14] or eight [15] N-methylated pyridoxy substituents at their periphery were provent ob ei nefficientf or the photodynamic inactivation of Gram-negative E. coli. In our recent study,w es howedt hat boronic acid functionality can confer activity to at etra-cationic silicon(IV) phthalocyanine by substantially increasing the local concentrationo fP S. [16] Greater photobactericidale fficacy of toluidine blue in comparison to methylene blue was also found to be due to the stronger interaction of the former with LPS components.…”