Novel Nanohybrids Based on Supramolecular Assemblies of Meso-tetrakis-(4-sulfonatophenyl) Porphyrin J-aggregates and Amine-Functionalized Carbon Nanotubes

Abstract

The ability of multiwalled carbon nanotubes (MWCNTs) covalently functionalized with polyamine chains of different length (ethylenediamine, EDA and tetraethylenepentamine, EPA) to induce the J-aggregation of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) was investigated in different experimental conditions. Under mild acidic conditions, protonated amino groups allow for the assembly by electrostatic interaction with the diacid form of TPPS, leading to hybrid nanomaterials. The presence of only one pendant amino group for a chain in EDA does not lead to any aggregation, whereas EPA (with four amine groups for chain) is effective in inducing J-aggregation using different mixing protocols. These nanohybrids have been characterized through UV/Vis extinction, fluorescence emission, resonance light scattering and circular dichroism spectroscopy. Their morphology and chemical composition have been elucidated through transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). TEM and STEM analysis evidence single or bundles of MWCNTs in contact with TPPS J-aggregates nanotubes. The nanohybrids are quite stable for days, even in aqueous solutions mimicking physiological medium (NaCl 0.15 M). This property, together with their peculiar optical features in the therapeutic window of visible spectrum, make them potentially useful for biomedical applications.

Controlling J-Aggregates Formation and Chirality Induction through Demetallation of a Zinc(II) Water Soluble Porphyrin

“…This experimental evidence has been explained with a dipolar coupling mechanism, more similar to metal colloids, rather than with the Frenkel exciton model, in the case of J-aggregates of the same porphyrin prepared in the presence of a series of cationic polyamines. [46,65,75] Indeed, as aggregation rates increase the J-band becomes more intense and sharp ( Figure 8) and correspondingly, the larger band in the CD spectra appears less evident. A similar behavior is displayed on increasing the ionic strength at fixed pH.…”

“…same porphyrin prepared in the presence of a series of cationic polyamines. [46,65,75] Indeed, as aggregation rates increase the J-band becomes more intense and sharp ( Figure 8) and correspondingly, the larger band in the CD spectra appears less evident. A similar behavior is displayed on increasing the ionic strength at fixed pH.…”

“…[11][12][13][14][15][16][17][18] Usually, chiroptical properties could arise from the presence of stereogenic centers in the basic building blocks, [19][20][21][22][23][24][25] or induced by a chiral scaffold or chemical template, such as simple chiral compounds, polymers and biomolecules. [26][27][28][29][30][31][32][33][34][35] Many examples of J-aggregated TPPS4 exhibiting optical activity under the presence of chemical [36][37][38][39][40][41][42][43][44][45][46][47] or physical chiral bias [48][49][50][51][52][53][54][55] have been reported so far. The occurrence of spontaneous symmetry breaking during the growth process has been related to kinetics and in particular to mixing protocols.…”

Role of Cobalt(III) Cationic Complexes in the Self-Assembling Process of a Water Soluble Porphyrin

“…Strong electronic coupling among the chromophores is responsible for resonant enhancement of Rayleigh [12][13][14][15][16][17][18][19][20] and Raman light scattering [21][22][23][24][25] and non-linear optical effects in large J-aggregates [26][27][28][29][30][31]. In addition, peculiar chiroptical properties emerge when these supramolecular systems grow in the presence of chemical [22,[32][33][34][35][36][37][38][39][40][41][42] or physical chiral bias [43][44][45][46][47][48][49][50]. Spontaneous symmetry breaking has been also reported [51,52], making a strong speculative point for the emergence of homochirality in life.…”

Novel Polymeric Composite TPPS/s-PEEK Membranes for Low Relative Humidity PEFC

“…TPPS J-aggregates are characterized by a linear arrangement of the chromophores and stabilized by electrostatic interactions between the negatively charged benzenesulfonate groups and the positively charged nitrogen atoms of the pyrrole rings, as well as by hydrogen bonds and stacking interactions [35][36][37][38][39][40]. Aggregation kinetics and final supramolecular structures are strictly related to the different experimental parameters, such as the nature of the acid [41], the ionic strength [38,39], organic or inorganic scaffold [42][43][44][45][46][47][48] or the reagent mixing order protocol [49,50]. In this work, the effect of different wt percentages of TPPS in s-PEEK membranes with a medium DS (50%) has been investigated.…”