Merging antimicrobial and visible emission properties within 1,3,4-trisubstituted-1,2,3-triazolium salts.

Bioactive molecules displaying visible wavelength emission can be useful for bioimaging, chemosensing and photodynamic therapy applications. Reported herein are 1,3,4-trisubsituted-1,2,3-triazolium salts displaying both antimicrobial and visible emission properties. Using a click chemistry approach, 2-fluorenyl, 1-naphthyl, 2-naphthyl, 2-anthracenyl and 1-pyrenyl units were incorporated at the N1 position, imparting visible emission properties to their triazolium bromide salts with Stokes shifts greater than 100 nm relative to the emission of their triazole precursors.

Synthetic Control of Exciton Dynamics in Bioinspired Cofacial Porphyrin Dimers.

Understanding how the complex interplay among excitonic interactions, vibronic couplings, and reorganization energy determines coherence-enabled transport mechanisms is a grand challenge with both foundational implications and potential payoffs for energy science. We use a combined experimental and theoretical approach to show how a modest change in structure may be used to modify the exciton delocalization, tune electronic and vibrational coherences, and alter the mechanism of exciton transfer in covalently linked cofacial Zn-porphyrin dimers ( linked and linked ). While both and feature zinc porphyrins linked by a 1,2-phenylene bridge, differences in the interporphyrin connectivity set the lateral shift between macrocycles, reducing electronic coupling in and resulting in a localized exciton.

Ru(II) coordination compounds of N-N bidentate chelators with 1,2,3 triazole and isoquinoline subunits: Synthesis, spectroscopy and antimicrobial properties.

Bidentate chelators 1-(1-benzyl-1,2,3-triazol-4-yl)isoquinoline and 3-(1-benzyl-1,2,3-triazol-4-yl)isoquinoline were prepared from benzyl bromide and trimethylsilylethynylisoquinoline precursors using a tandem deprotection/substitution/CuAAC synthetic approach. Each chelator is capable of forming a stable 3:1 Ru(II) coordination compound, which forms as a geometric isomer mixture. These Ru(II) complexes possess unique MLCT absorbance signatures at 450/472 nm (1-isomer) and 367 nm (3-isomer) relative to their constituent chelating units.

Antimicrobial 1,3,4-trisubstituted-1,2,3-triazolium salts.

A series of 1,3,4-trisubstituted-1,2,3-triazolium bromide salts were prepared by efficient two-step sequences of azide-alkyne cycloaddition and benzylic substitution. The antimicrobial activity of each triazolium salt and correlating triazole precursor was evaluated using a minimum inhibitory concentration (MIC) assay. MIC activities as low as 1 µM against Gram-positive bacteria, 8 µM against Gram-negative bacteria and 4 µM against fungi were observed for salt analogs, while neutral triazoles were inactive.

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles.

The 1-substituted-4-imino-1,2,3-triazole motif is an established component of coordination compounds and bioactive molecules, but depending on the substituent identity, it can be inherently unstable due to Dimroth rearrangements. This study examined parameters governing the ring-degenerate rearrangement reactions of 1-substituted-4-imino-1,2,3-triazoles, expanding on trends first observed by L'abbé et al. The efficiency of condensation between 4-formyltriazole and amine reactants as well as the propensity of imine products towards rearrangement was each strongly influenced by the substituent identity.

Tandem synthesis of 1-formyl-1,2,3-triazoles.

A tandem method for preparing 4-formyl-1,2,3-triazoles via a two-step one-pot acetal cleavage/CuAAC reaction was developed. Using this method, 4-formyl-1,2,3-triazole analogs with both electron-withdrawing and electron-donating substituents were prepared in good yield and purity. Expansion of this method to a three-step tandem reaction that incorporates an additional step of azide substitution was also successful, circumventing the need for organic azide isolation.

Spermine detection via metal-mediated ethynylarene 'turn-on' fluorescence signaling.

A dicarboxylated ethynylarene was shown to behave as a fluorescent chemosensor for millimolar concentrations of polyamines when mixed with Cd(II), Pb(II) or Zn(II) ions at micromolar concentrations. A bathochromic shift and intensification of fluorescence emission was observed with increasing amounts of metal ion in the presence of aqueous polyamines buffered at pH = 7.6.

Silver-Mediated Synthesis of Indolizines via Oxidative C-H functionalization and cyclization.

An efficient strategy for the synthesis of indolizines from readily available starting materials via oxidative C-H functionalization and cyclization in one step has been demonstrated. This protocol represents wide substrate scope, high functional group tolerance and selectivity. The structure of the product was confirmed by the X-ray crystallographic studies.

2-(1,2,3-Triazol-4-yl)pyridine-containing ethynylarenes as selective 'turn-on' fluorescent chemosensors for Ni(II).

A series of ethynylarene compounds containing 2-(1,2,3-triazol-4-yl)pyridine chelating units were studied as fluorescent chemosensors for metal cations in aqueous solution. Analogs possessing two chelating units bridged by either 1,4-diethynylphenyl or 2,7-diethynylnaphthyl subunits displayed large hypsochromic shifts coupled with signal intensification when exposed to increasing concentrations of Ni(II), a unique response among 22 metal cation analytes. This response was shown to be reversible, and is proposed to derive from disruption of aggregate formation upon Ni(II) binding at the peripheral chelating units.

Dicarboxylated ethynylarenes as buffer-dependent chemosensors for Cd(II), Pb(II) and Zn(II).

Two dicarboxylated ethynylarenes were prepared efficiently from condensation of 1,3-(3-aminoph enylethynyl)benzene with two equivalents of either succinic anhydride or glutaric anhydride. These compounds behave as fluorescent chemosensors selective for Cd(II), Pb(II) and Zn(II) cations under buffered aqueous conditions, with analyte binding observed as bathochromically shifted, intensified fluorescence. It was noteworthy that the fluorescence responses varied significantly with buffer identity.

Fast dye salts provide fast access to azidoarene synthons in multi-step one-pot tandem click transformations.

This study examined whether commercially available diazonium salts could be used as efficient aromatic azide precursors in one-pot multi-step click transformations. Seven different diazonium salts, including Fast Red RC, Fast Blue B, Fast Corinth V and Variamine Blue B were surveyed under aqueous click reaction conditions of CuSO(4)/Na ascorbate catalyst with 1:1 t-BuOH:H(2)O solvent. Two-step tandem reactions with terminal alkyne and diyne co-reactants led to 1,2,3-triazole products in 66%-88% yields, while three-step tandem reactions with trimethylsilyl-protected alkyne and diyne co-reactants led to 1,2,3-triazole products in 61%-78% yields.

A combinatorial approach to the discovery of biocidal six-residue cyclic D,L-alpha-peptides against the bacteria methicillin-resistant Staphylococcus aureus (MRSA) and E. coli and the biofouling algae Ulva linza and Navicula perminuta.

A combinatorial approach has been used to rapidly identify cyclic d,l-alpha-peptide hexamer sequences that exert biocidal activity towards both methicillin-resistant Staphylococcus aureus (MRSA) and E. coli bacteria, as well as the marine algae Ulva linza and Navicula perminuta. Evaluation of the effects against marine algae was facilitated by the development of a reliable, automated assay for toxicity, which should be of general utility for biofouling investigations.

Extreme electronic modulation of the cofacial porphyrin structural motif.

The synthesis, electrochemistry, and optical spectroscopy of an extensive series of cofacial bis[(porphinato)zinc(II)] compounds are reported. These species were synthesized using sequential palladium-catalyzed cross-coupling and cobalt-mediated [2+2+2] cycloaddition reactions. This modular methodology enables facile control of the nature of macrocycle-to-macrocycle connectivity and allows unprecedented modulation of the redox properties of face-to-face porphyrin species.

Strongly coupled porphyrin arrays featuring both pi-cofacial and linear-pi-conjugative interactions.

A combination of metal-catalyzed cross-coupling and metal-templated cycloaddition reactions have been utilized to establish multiporphyrin compounds 5-(5'-[15',15' '-bis(10' ',20' '-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)-6-[(5' "-10' ",20' "-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1) and 5,6-bis(5'-15',15' '-bis[(10',20'-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)indane (2). Compounds 1 and 2 feature a covalently bridged cofacial bis(porphinato)metal core; ethyne bridging moieties conjugate directly one and two respective peripheral (porphinato)zinc(II) substituents to the macrocyclic framework of their corresponding face-to-face porphyrin units. Optical spectroscopy and electrochemical studies demonstrate substantive electronic interactions between the porphyrin subunits of these compounds.