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The use of second-harmonic generation at different wavelengths to compare the resonant contributions of two simple dipolar chromophores, nitroaniline and nitrosulfenamide is reported. The result shows that pi intermolecular interaction does result in excitations that are observable in the linear spectrum of nitroaniline and thus could have an influence on the nonlinear response.

Organochalcogen-nitrogen heterocycles such as the 1,2,5-chalcogenadiazoles have a distinct tendency to establish intermolecular links in the solid state through secondary bonding interactions E...N (E=S, Se, Te). Because of its more polar character and lower-lying antibonding orbitals, the tellerium derivatives possess the strongest association energies.

Host defense (antimicrobial) peptides, produced by all complex organisms, typically contain an abundance of positively charged and hydrophobic amino acid residues. A small synthetic peptide termed innate defense regulator (IDR-)1018 was derived by substantial modification of the bovine neutrophil host defense peptide bactenecin. Here, we review its intriguing properties that include anti-infective, anti-inflammatory, wound healing, and anti-biofilm activities. It was initially developed as an immune modulator with an ability to selectively enhance chemokine production and polarize cellular differentiation while suppressing/balancing the pro-inflammatory response. In this regard, it has demonstrated in vivo activity in murine models including enhancement of wound healing and an ability to protect against Staphylococcus aureus, multidrug resistant Mycobacterium tuberculosis, herpes virus, and inflammatory disorders, including cerebral malaria and neuronal damage in a pre-term birth model. More recently, IDR-1018 was shown, in a broad-spectrum fashion, to selectively target bacterial biofilms, which are adaptively resistant to many antibiotics and represent the most common growth state of bacteria in human infections. Furthermore, IDR-1018 demonstrated synergy with conventional antibiotics to both prevent biofilm formation and treat pre-existing biofilms. These data are consistent with a strong potential as an adjunctive therapy against antibiotic-resistant infections. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Organochalcogen-nitrogen heterocycles such as the 1,2,5-chatcogenadiazOles have a distinct tendency to establish intermolecular links in the solid state through secondary bonding interactions E''N (E = S, Se, Te). The association of these molecules was examined in detail using relativistic density functional theory. Although there is an important electrostatic component, the interaction between these molecules is dominated by contributions arising from orbital mixing, which can be interpreted as the donation of a nitrogen lone pair into the chalcogen-centered antibonding orbitals. Because of its more polar character and lower-lying antibonding orbitals, the tellurium derivatives possess the strongest association energies; these are so large that the binding strength is comparable to that of some hydrogen bondsb In the absence of steric constraints, telluradiazoles associate in a coplanar fashion forming ribbon polymers. However, bulky susbstituents could be used to direct the formation of either helical chains or discrete dimers. In addition to its strength, the coplanar dimer is characterized by being rigid, yet no activation barrier is expected for the association/dissociation process. These attributes strongly indicate that tellurium-nitrogen heterocycles have great potential as building blocks in supramolecular architecture. [ABSTRACT FROM AUTHOR]

The "golden era" of antibiotic discovery has long passed, but the need for new antibiotics has never been greater due to the emerging threat of antibiotic resistance. This urgency to develop new antibiotics has motivated researchers to find new methods to combat pathogenic microorganisms resulting in a surge of research focused around antimicrobial peptides (AMPs; also termed host defense peptides) and their potential as therapeutics. During the past few decades, more than 2000 AMPs have been identified from a diverse range of organisms (animals, fungi, plants, and bacteria). While these AMPs share a number of common features and a limited number of structural motifs; their sequences, activities, and targets differ considerably. In addition to their antimicrobial effects, AMPs can also exhibit immunomodulatory, anti-biofilm, and anticancer activities. These diverse functions have spurred tremendous interest in research aimed at understanding the activity of AMPs, and various protocols have been described to assess different aspects of AMP function including screening and evaluating the activities of natural and synthetic AMPs, measuring interactions with membranes, optimizing peptide function, and scaling up peptide production. Here, we provide a general overview of AMPs and introduce some of the methodologies that have been used to advance AMP research.

The wavelength-dependent second-harmonic generation (SHG) efficiency of two simple dipolar chromophores, 4-NO2C6H4N(H)Bun (1) and 4-NO2C6H4SN(H)But (2), was compared in solution and in the solid state. Hyper-Rayleigh scattering measurements at 532 nm provided comparable molecular first hyperpolarizabilities. Both compounds crystallize in non-centrosymmetric space groups, but a more efficient arrangement of dipole moments results in a significantly larger deff value for 2. Kurtz-Perry experiments from 450 to 700 nm revealed an important difference in the resonant component of the nonlinear optical responses of these compounds; the SHG efficiency of crystalline 1 depends more strongly on the incident wavelength than that of 2. This would be in contradiction with the TD-DFT excitation energies calculated for these molecules, but the observation can be explained by the resonant contribution from low-energy interchromophore excitations enabled by pi-stacking in the crystal of 1.