Monthly Archives: September 2023

Tumor‐pH‐value responsive non‐peripheral substituted phthalocyanines: Synthesis, investigation of photophysical and photochemical properties

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Tumor-pH-value responsive non-peripheral substituted phthalocyanines: Synthesis, investigation of photophysical and photochemical properties


Cancer is one of the diseases with the highest mortality rate worldwide. Although PDT has recently produced encouraging outcomes, there are still many areas that need to be improved. The first of these is the negative consequences faced by patients treated with the PDT method when exposed to sunlight. For this reason, a new PDT method has been developed in recent years, and it is aimed at using photosensitizer molecules that can be active in acidic conditions. Since the pH values of tumor tissues are more acidic than normal tissues, preparing molecules that act effectively in acidic conditions will allow for more effective results in treating cancer with PDT. In this context, within the scope of this study, 3-(4-propionylphenoxy)phthalonitrile (1) and its non-peripheral tetra-substituted phthalocyanine derivatives [(2), (3), and (4)] were prepared. With these phthalocyanine derivatives, the novel compounds (5), (6), and (7) were synthesized for the first time. The aggregation tendencies of newly synthesized phthalocyanines (5–7) were investigated in solvent media. The effects of pH changes upon UV–Vis and fluorescence spectra were performed. The electronic and emission spectra of synthesized phthalocyanine derivatives are highly sensitive to pH changes. Formation constant (LogK) values of mono- and di-protonated phthalocyanine forms were calculated by the Henderson–Hasselback equation. The mono- and di-protonated species' equilibrium constants (logK1 and logK2) were calculated as ~5.0. This value may be promising for pH-sensitizing photosensitizers. Also, the photophysical and photochemical properties of synthesized metallophthalocyanine derivatives (2) and (5) were studied at different pH values. The singlet oxygen quantum yield of (2) and (5) was calculated to be 0.78 and 0.81 in DMSO, respectively. When pH = 6.4, that is, tumor-pH-values, this value for (5) has increased to 0.92. The newly synthesized phthalocyanines are suitable photosensitizers for PDT applications, especially with high singlet oxygen quantum yield at pH 6.4.

Theoretical insights into photo‐induced behavior for 3‐(1H‐phenanthro[9,10‐d]imidazol‐2‐yl)‐9‐phenyl‐9H‐carbazol‐4‐ol fluorophore: Solvation effects

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Theoretical insights into photo-induced behavior for 3-(1H-phenanthro[9,10-d]imidazol-2-yl)-9-phenyl-9H-carbazol-4-ol fluorophore: Solvation effects

Photo-induced excitation enhances intramolecular hydrogen bonding interactions for CHPHI compound. Enhanced hydrogen bond OH⋯N facilitates ESIPT tendency. ICT further promotes the occurrence of ESIPT reaction for CHPHI system. Nonpolar solvent environment is more favorable for ESIPT behavior of CHPHI fluorophore.


Abstract

Excited-state intramolecular proton transfer (ESIPT) reaction, as one of the most fundamental photochemical behaviors, plays a crucial role in the design of novel optical materials. This study investigates the photo-induced hydrogen bonding behaviors and related ESIPT process of 3-(1H-phenanthro[9,10-d]imidazol-2-yl)-9-phenyl-9H-carbazol-4-ol (CHPHI) in solvents with varying polarities. Based on analyses of the core-valence bifurcation (CVB) index, geometrical structure parameters, topological analysis, and infrared (IR) vibrational spectra, we infer that light excitation facilitates the enhancement of intramolecular hydrogen bonding. This phenomenon can promote the ESIPT process. In particular, we have observed that the enhancement of hydrogen bonding becomes more pronounced as solvent polarity weakens. To further investigate the relationship between solvent polarity and ESIPT behavior, we conduct an exploration of the frontier molecular orbitals (MOs) in CHPHI. Finally, by comparing the magnitudes of excited-state barriers in different solvents, we claim that nonpolar solvents drive the ESIPT reaction for CHPHI fluorophore.

Bubble Interfacial Area in a Swirling Contactor: Experiments and Computational Fluid Dynamics Simulations

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Bubble Interfacial Area in a Swirling Contactor: Experiments and Computational Fluid Dynamics Simulations

Swirling flows can be applied for gas-liquid mass transfer process intensification. Experiments and simulations were conducted to investigate the bubble size, gas holdup, and interfacial area in a swirling contactor which was divided into twelve subregions. Bubble breakup and coalescence processes between all bubble size classes were considered using appropriate models.


Abstract

The bubble size, gas holdup, and interfacial area in a swirling contactor were investigated through experiments and simulations. The interfacial area was obtained for liquids and gases with Reynolds numbers Re l and Re g, respectively. The contactor was divided into twelve subregions. Re l was negatively related to bubble size, gas holdup, and interfacial area, whereas Re g was positively associated. The maximum bubble interfacial area for the entire swirling contactor was 196.3 m−1 with a gas-liquid ratio of 0.022. There is a trade-off between centrifugal acceleration and bubble size for interfacial area.

Piper chaba, an Indian spice plant extract, inhibits cell cycle G1/S phase transition and induces intrinsic apoptotic pathway in luminal breast cancer cells

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Abstract

Piper chaba (Piperaceae) is a medicinal spice plant that possesses several pharmacological activities. In the present study, we for the first time studied the effect of P. chaba extract on breast cancer cells. P. chaba stem methanolic (PCSM) extract produced time and dose dependent cytotoxicity in luminal breast cancer cells (MCF-7 and T47D) with a minimal toxicity in breast normal cells (MCF-10A) at 10–100 µg/mL concentration. PCSM extract exerts 16.79 and 31.21 µg/mL IC50 for T47D and MCF-7 cells, respectively, in 48 h treatment. PCSM significantly arrests the T47D cells at the G0/G1 phase by reducing the CCND1 and CDK4 expression at mRNA and protein levels. PCSM extract treatment significantly altered nuclear morphology, mitochondria membrane potential, and production of reactive oxygen species in T47D cells at IC50 concentration. Extract treatment significantly altered the Bax/Bcl-2 ratio and altered caspase 8 and 3 mRNA/protein levels in T47D cells. Confocal microscopy showed an increase in late apoptosis in PCSM extract-treated breast cancer cells at IC50. Further, an increased caspase 9 and caspase 3/7 enzymatic activity was observed in test cells compared with nontreated cells. In conclusion, P. chaba phytocompound possesses the potential to induce cell cycle arrest and induce apoptosis in luminal breast cancer cells.

Industrial Fragrance Chemistry: A Brief Historical Perspective

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Perfumery has evolved from a handcraft activity, marking supreme aristocratic luxury in the Renaissance, to a global industry powering scent experiences for present-day consumers through the use of a myriad of consumer packaged goods. This contribution reviews major breakthroughs in the field, including landmark fragrance ingredients, technological advances in scent delivery, and key innovations in consumer products which created the demand for scientific and technological advancements in the scent domain. These innovations are presented chronologically, relying solely on information drawn from public written sources, spanning a time period of 150 years (1870-2020). We hope with this contribution to generate interest in the readership for this fascinating field, while celebrating 150 years of innovation for scented mass-market products..

Cucurbit[6]uril Hyperpolarized Chemical Exchange Saturation Transfer Pulse Sequence Parameter Optimization and Detectability Limit Assessment at 3.0T

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Molecular imaging is the future of personalized medicine; however, it requires effective contrast agents. Hyperpolarized chemical exchange saturation transfer (HyperCEST) can boost the signal of Hyperpolarized 129Xe MRI and render it a molecular imaging modality of high efficiency. Cucurbit[6]uril (CB6) has been successfully employed in vivo as a contrast agent for HyperCEST MRI, however its performance in a clinical MRI scanner has yet to be optimized. In this study, MRI pulse sequence parameter optimization was first performed in CB6 solutions in phosphate-buffered saline (PBS), and subsequently in whole sterile citrated bovine blood. The performance of four different depolarization pulse shapes (sinusoidal, 3-lobe sinc (3LS), rectangular (block), and hyperbolic secant (hypsec) was optimized. The detectability limits of CB6 in a clinical 3.0T MRI scanner was assessed using the optimized pulse sequences. The 3LS depolarization pulses performed best, and demonstrated 24% depletion in a 25µM solution of CB6 in PBS. It performed similarly in blood. The CB6 detectability limit was found to be 100µM in citrated bovine blood with a correspondent HyperCEST depletion of 30% ± 9%. For the first time, the HP 129Xe HyperCEST effect was observed in red blood cells (RBC) and had a similar strength as HyperCEST in plasma.

Atomically–Dispersed Metal Heterocatalysts: A Practical Step Toward Sustainability

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Atomically-dispersed heterogeneous metal catalysts can be considered as an “upgraded” version of classical solid metal catalysts. Unlike traditional heterogeneous metallic catalysts that contain nanoparticles or bulk micro-sized transition metal species, the active sites of these novel types of catalysts are atomically distributed on the support’s surface. This provides several advantages compared to classical catalysts such as higher activity and need for just very small amounts of metal precursors for the catalyst preparation. The latter issue is a key point in green chemical processes and of importance to achieve low-cost pathways for industrial-scale synthesis. The atomically dispersed metal sites permit a maximum of metal dispersion and additionally allow to achieve more reproducible heterogeneous catalysts. This review summarizes an overview on breakthrough findings in synthesis, applications and characterization techniques developed in the area of single-atom, dual-atom, single-atom-layer, single-site as well as single-atom nanozyme/enzyme catalysis. The characteristics and properties of each system provide an appropriate understanding for designing a nanomaterial that is optimized for a specific requirement.

Cyclometallated Platinum(II) Complexes Featuring an Unusual, C^N‐Coordinating Pyridyl‐pyridylidene Ligand and L X Coligands: Synthesis, Structures and Dual Luminescence Behavior

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Cyclometallated Platinum(II) Complexes Featuring an Unusual, C^N-Coordinating Pyridyl-pyridylidene Ligand and L X Coligands: Synthesis, Structures and Dual Luminescence Behavior


Abstract

Thanks to an unusual protodemethylation reaction, a series of luminescent cyclometallated platinum(II) complexes can be prepared, which incorporate a rare NC-chelating, pyridyl-pyridylidene ligand, in combination with OO-coordinating acetylacetonate (acac) or NO-coordinating 2-picolinate (pic) or 8-hydroxyquinolate.  The acac and pic complexes show unusual dual emission in a frozen glass.

A series of cyclometallated platinum(II) complexes incorporating a rare, N^C-chelating, pyridyl-pyridylidene ligand are described, in which the coordination sphere is completed by two chlorides or an L X co-ligand, namely O O-coordinating acetylacetonate (acac), or N^O-coordinating 2-picolinate (pic) or 8-hydroxyquinolinate. The acac and pic complexes have been structurally characterized in the solid state by single-crystal X-ray diffraction. These two complexes display red phosphorescence in the solid state at room temperature. In a frozen glass at 77 K, all four complexes show two broad emission bands that span much of the visible spectrum, apparently from two unequilibrated excited states.

Direct Synthesis of Aldoximes: Ruthenium‐Catalyzed Coupling of Alcohols and Hydroxylamine Hydrochloride

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Direct Synthesis of Aldoximes: Ruthenium-Catalyzed Coupling of Alcohols and Hydroxylamine Hydrochloride

A ruthenium pincer catalyzed direct synthesis of oximes from alcohols and hydroxyl amine hydrochloride salt is reported. Notably, the reaction requires only a catalyst and base, and water and liberated hydrogen are the only byproducts making this protocol attractive and environmentally benign.


Abstract

A catalytic method for the direct synthesis of oximes from alcohols and hydroxyl amine hydrochloride salt is reported. The reaction is catalyzed by a ruthenium pincer catalyst, which oxidizes alcohols involving amine-amide metal-ligand cooperation, and the in situ formed aldehydes condense with hydroxyl amine to deliver the oximes. Notably, the reaction requires only a catalyst and base; water and liberated hydrogen are the only byproducts, making this protocol attractive and environmentally benign.

Chemoenzymatic Tagging of Tn/TF/STF Antigens in Living Systems

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Chemoenzymatic Tagging of Tn/TF/STF Antigens in Living Systems


Abstract

Truncated mucin-type O-glycans, such as Tn-associated antigens, are aberrantly expressed biomarkers of cancer, but remain challenging to target. Reactive antibodies to these antigens either lack high affinity or are prone to antigen escape. Here, we have developed a robust chemoenzymatic strategy for the global labeling of Tn-associated antigens, i. e. Tn (GalNAcα-O-Ser/Thr), Thomsen-Friedenreich (Galβ1-3GalNAcα-O-Ser/Thr, TF) and STF (Neu5Acα2-3Galβ1-3GalNAcα-O-Ser/Thr, STF) antigens, in human whole blood with high efficiency and selectivity. This method relies on the use of the O-glycan sialyltransferase ST6GalNAc1 to transfer a sialic acid-functionalized adaptor to the GalNAc residue of these antigens. By tagging, the adaptor functionalized antigens can be easily targeted by customized strategies such as, but not limited to, chimeric antigen receptor T-Cells (CAR-T). We expect this tagging system to find broad applications in cancer diagnostics and targeting in combination with established strategies.