Malmbergbarefoot9421

A new efficient method was proposed for the synthesis of (18-crown-6)stilbene; the structure of the product was confirmed by X-ray diffraction analysis. In MeCN, this compound forms pseudodimeric complexes with N-(2-ammonioethyl)-4-styrylpyridinium and N-(3-ammoniopropyl)-4-styrylpyridinium diperchlorates via hydrogen bonding between the ammonium group and the crown ether oxygen atoms. The ammonioethyl derivative was synthesized for the first time. The stability constants and spectral characteristics of the complexes were measured by spectrophotometric and fluorescence titration. Photoirradiation of the pseudodimeric complex of (18-crown-6)stilbene with the ammoniopropyl dye resulted in the stereospecific [2 + 2] cross-photocycloaddition reaction. The replacement of the stilbene moiety in the crown compound by a styrylpyridine moiety led to a 5-fold increase in the quantum yield of the photoprocess. The most probable cause for this effect is the presence of photoinduced electron transfer in (18-crown-6)stilbene complexes. This assumption is confirmed by fluorescence lifetime spectroscopy and density functional theory calculations.Molecular triplet excitons produced through singlet fission (SF) usually have shorter triplet lifetimes due to exciton-exciton recombination and relaxation pathways, thereby resulting in complex device architectures for SF-boosted solar cells. Using broadband transient absorption spectroscopy, we here show that the photoexcitation of nanostructured lycopene H-aggregates at room temperature produces free triplets with an unprecedented 35-fold enhancement in the lifetime compared to those localized on the monomer backbone. The observed rise of a spectrally blue-shifted correlated T-T pair state in ∼19 ps with distinct vibronic features provides the basis for SF-induced triplet generation.Dinuclear iron centers with a bridging hydroxido or oxido ligand form active sites within a variety of metalloproteins. A key feature of these sites is the ability of the protein to control the structures around the Fe centers, which leads to entatic states that are essential for function. To simulate this controlled environment, artificial proteins have been engineered using biotin-streptavidin (Sav) technology in which Fe complexes from adjacent subunits can assemble to form [FeIII-(μ-OH)-FeIII] cores. The assembly process is promoted by the site-specific localization of the Fe complexes within a subunit through the designed mutation of a tyrosinate side chain to coordinate the Fe centers. An important outcome is that the Sav host can regulate the Fe···Fe separation, which is known to be important for function in natural metalloproteins. Spectroscopic and structural studies from X-ray diffraction methods revealed uncommonly long Fe···Fe separations that change by less than 0.3 Å upon the binding of additional bridging ligands. The structural constraints imposed by the protein host on the di-Fe cores are unique and create examples of active sites having entatic states within engineered artificial metalloproteins.Zinc-phthalocyanine (ZnPc) photosensitizers (PSs) have shown great potential in photodynamic therapy (PDT) owing to their strong absorption at long wavelengths (650-750 nm), high triplet quantum yields, and biocompatibility. However, the clinical utility of ZnPc PSs is limited by their poor solubility and tendency to aggregate in aqueous environments. Here we report the design of a new nanoscale metal-organic layer (nMOL) assembly, ZnOPPc@nMOL, with ZnOPPc [ZnOPPc = zinc(II)-2,3,9,10,16,17,23,24-octa(4-carboxyphenyl)phthalocyanine] PSs supported on the secondary building units (SBUs) of a Hf12 nMOL for PDT. Upon irradiation, SBU-bound ZnOPPc PSs absorb 700 nm light and efficiently sensitize the formation of singlet oxygen by preventing aggregation-induced self-quenching of ZnOPPc excited states. With intrinsic mitochondria-targeting capability, ZnOPPc@nMOL showed exceptional PDT efficacy with >99% tumor growth inhibition and 40-60% cure rates on two mouse models of colon cancer.Gram-negative bacteria, which possess an impermeable outer membrane, are responsible for many untreatable infections. The lack of development of new relevant antibiotics for over 50 years has increased threats. Ferrostatin1 Peptides are regarded as the most promising alternatives to antibiotics. However, since the activities of existing peptides are not yet comparable to those of current antibiotics, there is an urgent need to improve their antibacterial efficiencies. Herein, we conjugate peptides onto one-dimensional rod-like tobacco mosaic virus (TMV). The peptides on the obtained nanoparticles (peptide-TMV) are hundreds of times superior to free peptides in combating Gram-negative bacteria. Through morphology and gene detection of Escherichia coli, it was revealed that following peptide-TMV application, the high osmotic pressure related to membrane damage and the generated reactive oxygen species cause Escherichia coli's death. In addition, peptide-TMV causes a downregulation of biofilm-related genes, inhibiting biofilm formation. This work paves the way to combat Gram-negative bacteria-related infection.Two derivatives of dansyl (1-dimethylamino-5-naphthalenesulfonyl) in which the amino group is constrained in a ring are prepared as neopentyl esters. Their photophysical behavior is compared with that of the dansyl ester. The solvatochromism and quantum yields are similar for all three. Since the two constrained derivatives cannot twist about the amino group, they must emit from a planar intramolecular charge-transfer excited state. The similar photophysical behavior suggests that dansyl also emits from a PICT excited state instead of a twisted intramolecular charge transfer state.The natural β-carboline alkaloids display similarities with neurotransmitters that can be favorably exploited to design bioactive and bioavailable drugs for Alzheimer's disease (AD) therapy. Several AD targets are currently and intensively being investigated, divided in different hypotheses mainly the cholinergic, the amyloid β (Aβ), and the Tau hypotheses. To date, only symptomatic treatments are available involving acetylcholinesterase and NMDA inhibitors. On the basis of plethoric single-target structure-activity relationship studies, the β-carboline scaffold was identified as a powerful tool for fostering activity and molecular interactions with a wide range of AD-related targets. This knowledge can undoubtedly be used to design multitarget-directed ligands, a highly relevant strategy preferred in the context of multifactorial pathology with intricate etiology such as AD. In this review, we first individually discuss the AD targets of the β-carbolines, and then we focus on the multitarget strategies dedicated to the deliberate design of new efficient scaffolds.