Design, Synthesis, and Utility of Defined Molecular Scaffolds

A growing theme in chemistry is the joining of multiple organic molecular building blocks to create functional molecules. Diverse derivatizable structures—here termed “scaffolds” comprised of “hubs”—provide the foundation for systematic covalent organization of a rich variety of building blocks. This review encompasses 30 tri- or tetra-armed molecular hubs (e.g., triazine, lysine, arenes, dyes) that are used directly or in combination to give linear, cyclic, or branched scaffolds. Each scaffold is categorized by graph theory into one of 31 trees to express the molecular connectivity and overall architecture. Rational chemistry with exacting numbers of derivatizable sites is emphasized. The incorporation of water-solubilization motifs, robust or self-immolative linkers, enzymatically cleavable groups and functional appendages affords immense (and often late-stage) diversification of the scaffolds. Altogether, 107 target molecules are reviewed along with 19 syntheses to illustrate the distinctive chemistries for creating and derivatizing scaffolds. The review covers the history of the field up through 2020, briefly touching on statistically derivatized carriers employed in immunology as counterpoints to the rationally assembled and derivatized scaffolds here, although most citations are from the past two decades. The scaffolds are used widely in fields ranging from pure chemistry to artificial photosynthesis and biomedical sciences.

Water solubilization of paclitaxel using polypeptides for cancer therapy

To address problems in drug discovery, we developed approaches to solubilize hydrophobic compounds using polypeptides including poly-L-lysine (PLL) via high-speed vibration milling. The current method can be used to prepare...

Bioconjugatable synthetic chlorins rendered water-soluble with three PEG-12 groups via click chemistry

Chlorins provide many ideal features for use as red-region fluorophores but require molecular tailoring for solubilization in aqueous solution. A chlorin building-block bearing 18,18-dimethyl, 15-bromo and 10-[2,4,6-tris(propargyloxy)phenyl] substituents has been transformed via click chemistry with CH3(OCH2CH[Formula: see text]-N3 followed by Suzuki coupling with 3-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)propanoic acid, thereby installing a water-solubilization motif and a bioconjugatable handle, respectively. In toluene, [Formula: see text]-dimethylformamide (DMF) or water, the resulting facially encumbered free base chlorin exhibits characteristic chlorin absorption ([Formula: see text] [Formula: see text]412, 643 nm) and fluorescence ([Formula: see text] [Formula: see text]645 nm) spectra with only modest variation in fluorescence quantum yield ([Formula: see text] values (0.24, 0.25 and 0.19, respectively). The zinc chlorin derived therefrom exhibits similar spectral constancy ([Formula: see text] [Formula: see text]414 and 613 nm, [Formula: see text] [Formula: see text]616 nm) and [Formula: see text] 0.094, 0.10 and 0.086 in the three solvents. The results together indicate the viability of the molecular design and synthetic methodology to create red-region fluorophores for use in diverse applications.

Combustible Microemulsions with Diesel and Diesel Admixed with Rapeseed Oil

Novel results on combustible microemulsions prepared with diesel (D), blends of diesel and rapeseed oil (RSO), and mixtures of eco-friendly amphiphiles are presented. Water solubilization in oil/amphiphile systems was estimated by pseudo-ternary diagrams whereas the phase behavior by Winsor (W) diagrams. The extent of single-phase microemulsion (SPM) area depends on the amphiphile and oil phase composition. The presence of cosurfactant in the anionic-nonionic surfactant mixture increases very much the SPM area, but no effect is observed when half of D is replaced by RSO. In the pseudo-ternary phase diagram, the addition of organic electrolyte decreases the SPM areas. The microemulsions were characterized by the oil/water interfacial tension (gow), and the oil and water solubilization parameters (SPo) and (SPw). The results obtained reveal that the W III microemulsions have minimal goow values, whereas SPo and SPw are maximal. The work connects the phase behavior with the interfacial tension and the solubilization parameters of oil and water and is useful for obtaining and developing optimal microemulsions as alternative fuels.

Photoproperties, PVP formulation and 19F NMR of a Zn phthalocyanine with 24 magnetically pseudo-equivalent fluorine atoms

In an attempt to investigate its potential as a PDT [Formula: see text]F MRI molecular theranostic, a Zn phthalocyanine with 24 pseudo-equivalent fluorine atoms was designed and prepared. Compared to its H analogues, the fluorinated derivative has a much higher generation of singlet oxygen. [Formula: see text]F NMR signals in CDCl3 showed that all the fluorine atoms are magnetically pseudo-equivalent with only two close fluorine signals. Formulation in PVP (polyvinylpyrrolidone), a FDA-approved additive, enabled water-solubilization of the phthalocyanines but no satisfying [Formula: see text]F NMR signal could be obtained, probably due to self-quenching caused by aggregation.