Unlocking Solid-State Organometallic Photochemistry with Optically Transparent, Porous Salt Thin Films.

Synthetic porous materials continue to garner attention as platforms for solid-state chemistry and as designer heterogeneous catalysts. Applications in photochemistry and photocatalysis, however, are plagued by poor light harvesting efficiency due to light scattering resulting from sample microcrystallinity and poor optical penetration that arises from inner filter effects. Here we demonstrate the layer-by-layer growth of optically transparent, photochemically active thin films of porous salts. Films are grown by sequential deposition of cationic Zr-based porous coordination cages and anionic Mn porphyrins. Photolysis facilitates the efficient reduction of Mn(III) sites to Mn(II) sites, which can be observed in real-time by transmission UV-vis spectroscopy. Film porosity enables substrate access to the Mn(II) sites and facilitates reversible O2 activation in the solid state. These results establish optically transparent, porous salt thin films as versatile platforms for solid-state photochemistry and in operando spectroscopy.

Divergent Synthesis of Chelating Aziridines and Cyclic(Alkyl)(Amino)Carbenes (CAACs) from Pyridyl-Tethered Robust Azomethine Ylides.

Azomethine ylides are typically in situ generated synthons for making N-heterocycles through cycloaddition reactions. But an offbeat aspect about them is the isomeric nature of aldiminium-based azomethine ylides and (alkyl/aryl)(amino)carbenes, interconvertible by a formal 1,3-H+ transfer. Herein, two thermally robust azomethine ylides with a N-appended picolyl sidearm are isolated, which cyclize to py aziridines at 80 °C but unprecedentedly result N-pico CAAC-CuCl (CAAC=cyclic(alkyl)(amino)carbene) complexes when heated with CuCl at merely 60 °C. The pendant Npy , as revealed by computational analysis, plays a crucial role in this unusual 1,3-H+ shift using a deprotonation-protonation sequence, as well as in placing the CuCl at the carbenic site in tandem. The softer nature of Cu(I) is also critical. Chelating CAACs are rare and one with a N-tethered additional donor is priorly unknown. Both N-pico CAAC and py aziridine are bidentate chelators giving highly active cationic Rh(I) catalysts for hydrosilylating unactivated olefins by Et3 SiH. Notably, the py aziridine-Rh(I) is superior than the N-pico CAAC-Rh(I) catalyst.

Identification of novel genetic and epigenetic regulators of different tissue types of cervical cancer.

OBJECTIVES: The study aimed to find differential gene mutations, DNA methylation, and expression profiles among different categories of cervical cancer samples. METHODS: The study was based on freely available gene mutations, promoter methylation, and gene expression status of The Cancer Genome Atlas (TCGA) cervical cancer samples and adjacent normal tissues in the Genomic Data Commons (GDC) portal. The association of CpG island methylation with gene expression was determined through negative correlation analysis. RESULTS: We identified that the ErbB signaling pathway and proteoglycans pathway was significantly associated with adenocarcinoma cervical cancers patients. In these pathways, missense mutation especially S310F in the ERBB2 gene as well as G12D and A146T in the KRAS gene were significantly associated with adenocarcinoma cases. Furthermore, a comparison of SCC cases with adjacent control tissues revealed differential hypermethylation of two CpG positions of the KAAG1 gene and differential downregulation of NPY1R and NPY5R genes in cervical squamous cell carcinoma compared to cervical adenocarcinoma cases and adjacent normal tissues. Specifically, the hypermethylation of the promoter region of the KAAG1 gene might be responsible for the carcinogenesis of cervical squamous cells exclusively and methylation marks can be reversible by the widely used drug, azacytidine. In contrast, adenocarcinoma cervical cancer cases may be treated with floxuridine which is successfully utilized for other tissue-specific adenocarcinoma cases. CONCLUSIONS: These results provide valuable insight into the differential molecular markers among the categories of cervical cancer, which helps our ability to classify these cancers and for targeted therapy.

Fluorenyl-tethered N-heterocyclic carbene (NHC): an exclusive C-donor ligand for heteroleptic calcium and strontium chemistry.

Exclusive C-donating ligands are rarely used with kinetically labile heavier alkaline earths (Ca, Sr, Ba). We report herein the aptitude of a combination of NHC with fluorenyl connected by a flexible -(CH2)2- linker as a ligand support for heteroleptic Ca- and Sr-N(SiMe3)2 and iodides. The Ca-N(SiMe3)2 complex even catalyzes the intramolecular hydroamination of aminoalkenes to showcase the effectiveness of this ligand framework.

Flexible NHC-aryloxido aluminum complex and its zwitterionic imidazolium aluminate precursor in ring-opening polymerization of ε-caprolactone.

Anionic donor-functionalized NHC (N-heterocyclic carbene) complexes of Al are rare. We report one such case here, an NHC-aryloxido AlMe2 complex [Al(L)Me2] (2), following a stepwise synthesis from the proligand [HO-4,6-tBu2-C6H2-2-CH2{CH(NCHCHNAr)}]Br [LH2Br; Ar = 2,6-iPr2-C6H3 (Dipp)] and AlMe3via the zwitterionic intermediate [Al(LH)Me2Br] (1). The ligand's flexibility in 2 is evident from the conformational fluxionality revealed by VT-1H NMR spectroscopic analysis. The ∠O-Al-C (ca. 100.5°) bite angle is also wider than the ∠O-Ti-C (ca. 80.6°) as seen in our recently reported Ti complex [Ti(L)(NMe2)2Br]. DFT analysis showed that the CNHC-Al bond is significantly ionic, as is the CNHC-Ti bond. Both 1 and 2 are active in the ring-opening polymerization (ROP) of ε-caprolactone (CL). 2, similar to [Ti(L)(NMe2)2Br], exhibits bifunctional MLC-type monomer activation, but only at an elevated temperature. However, the 2/BnOH combination is catalytically active at room temperature, likely through a zwitterionic [Al(LH)Me2(OBn)]. The 1/BnOH combination follows a similar mechanism but surprisingly at a faster rate.

Autofluorescence-spectral imaging for rapid and invasive characterization of soybean for pre-germination anaerobic stress tolerance.

The autofluorescence-spectral imaging (ASI) technique is based on the light-emitting ability of natural fluorophores. Soybean genotypes showing contrasting tolerance to pre-germination anaerobic stress can be characterized using the photon absorption and fluorescence emission of natural fluorophores occurring in seed coats. In this study, tolerant seeds were efficiently distinguished from susceptible genotypes at 405 nm and 638 nm excitation wavelengths. ASI approach can be employed as a new marker for the detection of photon-emitting compounds in the tolerant and susceptible soybean seed coats. Furthermore, the accuracy of rapid characterization of genotypes using this technique can provide novel insights into soybean breeding.