for Diagnostics and Therapeutics Sunaina Singh,*,†,∥ Amit Aggarwal,*,†,∥ N. V. S. Dinesh K. Bhupathiraju,*,‡ Gianluca Arianna,‡ Kirran Tiwari,‡ and Charles Michael Drain‡,§ †Department of Natural Sciences, LaGuardia Community College of the City University of New York, Long Island City, New York 11101, United States ‡Department of Chemistry and Biochemistry, Hunter College of the City University of New York, New York, New York 10065, United States The Rockefeller University, New York, New York 10065, United States

Glycosylated Porphyrins, Phthalocyanines, and Other Porphyrinoids for Diagnostics and Therapeutics.

Porphyrins and metalloporphyrins: versatile circular dichroic reporter groups for structural studies.

Chirality seems to be intimately associated with the growth and stability of self-assembled fibrillar networks and with the most common macroscopic property of these networks, which is the thermoreversible gelation of the solvent. The presence and the relative configurations of stereogenic centers in the structure of a small molecule gelator are generally (but not always) observed to be critical to its ability to form gels. Symmetry considerations of chiral molecular packing provide thermodynamic and kinetic arguments that may explain why chirality favors fiber growth. Additionally, molecular chirality is sometimes expressed at a scale of nanometers or micrometers and gives rise to twisted or coiled fiber structures that are readily observable by microscopic techniques. These chiral fiber morphologies have already found some applications as templates for helical protein crystallization or for the growth of chiral inorganic replicas. The chiroptical properties of assembled chiral molecules, e.g., circular dichroism, allow monitoring of aggregation and may sometimes give insights into molecular packing. But determining chiral molecular arrangements in the fibers remains a challenge and requires the use of multiple techniques.

Chirality Effects in Self-assembled Fibrillar Networks.

Nanotubes Self-Assembled from Amphiphilic Molecules via Helical Intermediates

A rational approach to the design of supramolecular organogels of all-trans oligo(p-phenylene vinylene) (OPV) derivatives, a class of well-known organic semiconductor precursors, is reported. Self-assembly of these molecules induced gelation of hydrocarbon solvents at low concentrations (<1 mM), resulting in high aspect ratio nanostructures. Electron microscopy and atomic force microscopy (AFM) studies revealed twisted and entangled supramolecular tapes of an average of 50-200 nm in width, 12-20 nm in thickness, and several micrometers in length. The hierarchical growth of the entangled tapes and the consequent gelation is attributed to the lamellar-type packing of the molecules, facilitated by cooperative hydrogen bonding, pi stacking, and van der Waals interactions between the OPV units. Gelation of OPVs induced remarkable changes in the absorption and emission properties, which indicated strong electronic interaction in the aggregated chromophores. Comparison of the absorption and emission spectra in the gel form and in the solid film indicated a similar chromophore organization in both phases. The presence of self-assembled aggregates of OPVs was confirmed by solvent- and temperature-dependent changes in the absorption and emission properties, and by selective excitation experiments. This is the first detailed report of the gelation-induced formation of OPV nanotapes, assisted by weak, nondirectional hydrogen-bonding motifs and pi-pi stacking. These findings may provide opportunities for the design of a new class of functional soft materials and nanoarchitectures, based on pi-conjugated organic semiconductor-type molecules, thereby enabling the manipulation of their optical properties.

Self‐Assembled Nanotapes of Oligo(p‐phenylene vinylene)s: Sol–Gel‐Controlled Optical Properties in Fluorescent π‐Electronic Gels

Some water-soluble porphyrins aggregate in aqueous media to form fibrous assemblies. When polynucleotides are used as matrices, porphyrin monomers are aligned at the periphery or intercalated. Porphyrin-porphyrin interactions hardly occur. Metal-metal or metal-ligand-metal interactions have been observed in oxo-oligomers, pyrazine-bridged dimers and radical dimers. β-Substituted metallo-porphyrins, however, form no polymers. The only linear polymerization, which has so far been observed in molecular asemblies, occurs with amphiphilic porphyrin amides, amines and carboxylates and their metal complexes in water and of bacteriochlorophyll in DMF/water. These compounds form long-lived high molecular weight micellar, inverse micellar and vesicular fibers spontaneously in aqueous media. The porphyrin fibers in water are about 4-6 nm thick and up to several of μm long.

Polymeric porphyrin and metalloporphyrin assemblies in bulk solution

Kristallstruktur einer racemischen Lipid‐Doppelschicht bestimmt mit Synchrotronstrahlung

The fully reversible synthesis of noncovalent assemblies which are held together by directed bonds is called synkinesis Micellar fibres with a distinct stereochemistry and gels are formed by amphiphiles forming strong hydrogen bonds between chiral head groups The 3D-crystallization of such molecular assemblies, without dominating repulsive hydration forces, is prevented by the curvature of the fibres Curvature might perhaps be directly connected with chirality Addition of enantiomers often leads to an irreversible destruction of gels Recent developments relating to ‘hydrophobic water’ in Angstrom-wide membrane gaps are also shortly discussed

/pdf/non-covalent-chiral-fibres-in-aqueous-gels-and-their-1m4cdt1hf2.pdf

Non-covalent chiral fibres in aqueous gels and their functionalization

Easily accessible protoporphyrin IX 13,17-bis(glycosamides) form colloidal aqueous solutions which are stable for several months or longer. Electron micrographs show ribbons of an approximate width of 4 nm and lengths of between 20 nm (D-glucosamide) and 5 μm (D,L-mannosamide). In one case, gel chromatography was applied in order to acquire the molecular weight, which was determined to be ≥2×10 6 D for about 90% of the colloidal particles. The UV-vis spectra of the aqueous suspension show a Soret band which is split by about 100 nm by exciton interactions (460 and 360 nm)

Chiral micellar porphyrin fibers with 2-aminoglycosamide head groups

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Polymeric porphyrin and metalloporphyrin assemblies in bulk solution

Kristallstruktur einer racemischen Lipid‐Doppelschicht bestimmt mit Synchrotronstrahlung

Non-covalent chiral fibres in aqueous gels and their functionalization

Chiral micellar porphyrin fibers with 2-aminoglycosamide head groups