Confinement Effect of Micro- and Mesoporous Materials on the Spectroscopy and Dynamics of a Stilbene Derivative Dye

Porphyrin J-aggregates as a probe for chiral impurities as demonstrated by their symmetry breaking by confinement in montmorillonite clay

In this paper, we demonstrate that chiral J-aggregates of porphyrins are able to detect minute chiral impurities, in this case, the presence of right-handed quartz in acid-activated K10 montmorillonite clay. Aggregation and symmetry breaking of 5,10,15,20-(tetra-4-carboxyphenyl) porphyrin (TCPP) and 5,10,15,20-(tetra-4-sulfonatophenyl) porphyrin (TPPS) were observed upon interaction with acid-activated montmorillonite clay (MMT-K10). A panel of characterization techniques, including UV-visible, electronic circular dichroism, IR, and vibrational circular dichroism spectroscopies, as well as X-ray scattering, were employed to investigate the aggregation of the confined TPPS and TCPP. An intriguing and persistent negative exciton effect was detected in the electronic circular dichroism spectra at the early stages of J-aggregation. The enrichment of a right-handed quartz impurity in the clay detected by vibrational circular dichroism may explain the symmetry breaking in the porphyrin assemblies. As a result, we propose that chiral porphyrin aggregates could serve as innovative probes for detecting subtle chirality in inorganic nanomaterials.

A primitive cell model involving Vesicles, microtubules and asters

HYPOTHESIS

Simple single-chain amphiphiles (sodium monododecyl phosphate, SDP) and organic small molecules (isopentenol, IPN), both of primitive relevance, are proved to have been the building blocks of protocells on the early Earth. How do SDP-based membrane and coexisting IPN come together in specific ways to produce more complex chemical entities? What kind of cell-like behavior can be endowed with this protocell model? These are important questions in the pre-life chemical origin scenario that have not been answered to date.

EXPERIMENTS

The phase behavior and formation mechanism of the aggregates for SDP/IPN/H2O ternary system were characterized and studied by different electron microscopy, fluorescent probe technology, DLS, IR, ESI-MS, SAXS, etc. The stability (freeze-thaw and wet-dry treatments) and cell-like behavior (chemical signaling communication) were tested via simulating particular scenarios.

FINDINGS

Vesicles, microtubules and asters phases resembling the morphology and structure of modern cells/organelles were obtained. The intermolecular hydrogen bonding is the main driving force for the emergence of the aggregates. The protocell models not only display remarkable stabilities by simulating the primordial Earth's diurnal temperature differences and ocean tides but also are able to exhibit cell-like behavior of chemical signaling transition.

Red-Emitting Polymerizable Guanidinium Dyes as Fluorescent Probes in Molecularly Imprinted Polymers for Glyphosate Detection

The development of methodologies to sense glyphosate has gained momentum due to its toxicological and ecotoxicological effects. In this work, a red-emitting and polymerizable guanidinium benzoxadiazole probe was developed for the fluorescence detection of glyphosate. The interaction of the fluorescent probe and the tetrabutylammonium salt of glyphosate was studied via UV/vis absorption and fluorescence spectroscopy in chloroform and acetonitrile. The selective recognition of glyphosate was achieved by preparing molecularly imprinted polymers, able to discriminate against other common herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (dicamba), as thin layers on submicron silica particles. The limits of detection of 4.8 µM and 0.6 µM were obtained for the sensing of glyphosate in chloroform and acetonitrile, respectively. The reported system shows promise for future application in the sensing of glyphosate through further optimization of the dye and the implementation of a biphasic assay with water/organic solvent mixtures for sensing in aqueous environmental samples.

Interrogating the Behaviour of a Styryl Dye Interacting with a Mesoscopic 2D-MOF and Its Luminescent Vapochromic Sensing

In this contribution, we report on the solid-state-photodynamical properties and further applications of a low dimensional composite material composed by the luminescent trans-4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) dye interacting with a two-dimensional-metal organic framework (2D-MOF), Al-ITQ-HB. Three different samples with increasing concentration of DCM are synthesized and characterized. The broad UV-visible absorption spectra of the DCM/Al-ITQ-HB composites reflect the presence of different species of DCM molecules (monomers and aggregates). In contrast, the emission spectra are narrower and exhibit a bathochromic shift upon increasing the DCM concentration, in agreeance with the formation of adsorbed aggregates. Time-resolved picosecond (ps)-experiments reveal multi-exponential behaviors of the excited composites, further confirming the heterogeneous nature of the samples. Remarkably, DCM/Al-ITQ-HB fluorescence is sensitive to vapors of electron donor aromatic amine compounds like aniline, methylaniline, and benzylamine due to a H-bonding-induced electron transfer (ET) process from the analyte to the surface-adsorbed DCM. These findings bring new insights on the photobehavior of a well-known dye when interacting with a 2D-MOF and its possible application in sensing aniline derivatives.

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

The Physical Chemistry and Chemical Physics Section (PCCP Section) is one of the youngest among the sections of the International Journal of Molecular Sciences (IJMS)-the year 2021 will only mark three years since its inception [...].