New BODIPY Dyes Based on Benzoxazole as Photosensitizers in Radical Polymerization of Acrylate Monomers

A series of 2-phenacylbenzoxazole difluoroboranes named BODIPY dyes (1–8) was designed and applied as photosensitizers (PS) for radical photopolymerization of acrylate monomer. The light absorption within the ultraviolet-visible (UV–Vis) range (λmax = 350–410 nm; εmax = 23,000–42,500 M−1cm−1), that is strongly influenced by the substituents on the C3 and C4 atoms of phenyl ring, matched the emission of the Omnicure S2000 light within 320–500 nm. The photosensitizer possess fluorescence quantum yield from about 0.005 to 0.99. The 2-phenacylbenzoxazole difluoroboranes, together with borate salt (Bor), iodonium salt (Iod) or pyridinium salt (Pyr) acting as co-initiators, can generate active radicals upon the irradiation with a High Pressure Mercury Lamp which initiates a high-performance UV–Vis light-induced radical polymerization at 320–500 nm. The polymers obtained are characterized by strong photoluminescence. It was found that the type of radical generator (co-initiator) has a significant effect on the kinetic of radical polymerization of acrylate monomer. Moreover, the chemical structure of the BODIPY dyes does not influence the photoinitiating ability of the photoinitiator. The concentration of the photoinitiating system affects the photoinitiating performance. These 2-phenacylbenzoxazole difluoroborane-based photoinitiating systems have promising applications in UV–Vis-light induced polymerization.

Effects of molecular geometry on the efficiency of intramolecular charge transfer–based luminescence in o-carboranyl-substituted 1H-phenanthro[9,10-d]imidazoles

Herein, we compared the optical properties of four compounds with an o-carborane cage linked to 1H-phenanthro[9,10-d]imidazole at the ortho- (oPC), meta- (mPC), or para-position (pPC) of the 2-phenyl ring or...

Effect of Methoxy Group/s on D-π-A Porphyrin Based DSSC: Efficiency Enhanced by Co-Sensitization

We have engineered, synthesized, characterized a series of porphyrin sensitizers which contain either three or one methoxy group/s on phenyl ring of triphenyl imidazole donor moiety with either 3-(5-(benzo[c][1,2,5]thiadiazole-4-yl)thiophene-2-yl)-2-cyanoacrylic acid...

Crystal structure and molecular docking study of diethyl 2,2′-({[(1E,1′E)-(hydrazine-1,2-diylidene)bis(methanylylidene)]bis(4,1-phenylene)}bis(oxy))diacetate

The title Schiff base, C22H24N2O6, adopts an E configuration. The molecule is planar, the mean planes of the phenyl ring system (r.m.s deviation = 0.0059 Å) forms a dihedral angle of 0.96 (4)° with the mean plane of the phenyl ring moiety (r.m.s deviation = 0.0076 Å). In the crystal, molecules are linked by weak intermolecular C—H...O and C—H...N hydrogen bonds into chains extending along the c-axis and b-axis directions, respectively. A molecular docking study between the title molecule and 5-HT2C, which is a G protein receptor and ligand-gated ion channels found in nervous systems (PDB ID: 6BQH) was executed. The experiment shows that it is a good potential agent because of its affinity and ability to stick to the active sites of the receptor.

Synthesis of β-Enaminonitrile-Linked 8-Methoxy-1H-Benzo[f]Chromene Moieties and Analysis of Their Antitumor Mechanisms

A series of aryl-substituted 3-amino-1-aryl-8-methoxy-1H-benzo[f]chromene-2-carbonitriles (4a–4q) were designed and synthesized via reaction of 6-methoxy-2-naphthol with a mixture of appropriate aromatic aldehydes and malononitrile under microwave conditions. The structures of the novel compounds 4b, 4c, 4f, 4g, 4i, 4l, 4m, and 4o–4q were established according to IR, 1H-NMR, 13C-NMR/13C-NMR-DEPT, and MS. The benzochromene derivative 4c with a single chlorine at the meta position of the phenyl ring and, to a lesser extent, other benzochromenes with monohalogenated phenyl ring (4a, 4c–4f) exhibited the highest cytotoxicity against six human cancer cell lines MDA-MB-231, A549, HeLa, MIA PaCa-2, 5,637, and Hep G2. The mechanisms of the cytotoxic activities of benzochromenes with monohalogenated phenyl ring (4a, 4c–4f) were further analyzed using triple-negative breast cancer cell line MDA-MB-231. Cell cycle analysis showed accumulation of the treated cells in S phase for 4a, 4d–4f, and S-G2/M phases for 4c. In vivo, 4a and 4c–4f inhibited growth, proliferation, and triggered apoptosis in preestablished breast cancer xenografts grown on the chick chorioallantoic membranes while exhibiting low systemic toxicity. Compounds 4a and 4c–4f increased levels of mitochondrial superoxide and decreased mitochondrial membrane potential resulting in initiation of apoptosis as demonstrated by caspase 3/7 activation. In addition, 4c induced general oxidative stress in cancer cells. The SAR study confirmed that halogens of moderate size at meta or para positions of the pendant phenyl ring enhance the cytotoxic activity of 3-amino-1-aryl-8-methoxy-1H-benzo[f]chromene-2-carbonitriles, and these compounds could serve as leads for the development of novel anticancer therapies.

Synthesis of typical sulfonamide antibiotics with [14C]- and [13C]-labelling on phenyl ring for environmental studies

Background As a kind of widely used antibiotics, sulfonamide antibiotics (SAs) has become ubiquitous environmental contaminants that caused public concerns. The behavior of SAs in complex environmental system need to be elucidated, which is hampered by unavailability or high cost of isotope-labelled SAs. Results Using commercially available uniformly [l4C]- and [l3C]-labelled aniline as starting material, we synthesized [phenyl-ring-14C]- and [phenyl-ring-l3C]-labelled sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ) using four-step (via condensation of labelled N-acetylsulfanilyl chloride and aminoheterocycles) or five-step (via condensation of labelled N-acetylsulfonamide and chloroheterocycles) reactions in good yields (5.0−22.5% and 28.1−54.1% for [14C]- and [13C]-labelled SAs, respectively) and high purities (> 98.0%). Conclusion The synthesis of [l4C]-labelled SAs could be completed on milligram-level, being feasible for preparation of labelled SAs with high specific radioactivity. This study provides efficient and maneuverable methods to obtain a variety of [14C]- or [13C]-labelled SAs for studies on their environmental behavior, such as fate, transformation, and bioaccumulation.

Synthesis and antimicrobial activity of aryldiazenyl/arylhydrazono pyrazoles

We report the design, synthesis, and in vitro antimicrobial evaluation of functionalized pyrazoles containing a hydrazono/diazenyl moiety. Among these newly synthesized derivatives, 4-[2-(4-chlorophenyl)hydrazono]-5-methyl-2-[2-(naphthalen-2-yloxy)acetyl]-2,4-dihydro-3 H-pyrazol-3-one is a promising antimicrobial agent against Staphylococcus aureus (minimum inhibitory concentration 0.19 μg mL−1). Structure–activity relationship studies reveal that the electronic environment on the distal phenyl ring has a considerable effect on the antimicrobial potential of the hybrid analogues. Molecular docking studies into the active site of S. aureus dihydrofolate reductase also prove the usefulness of hybridizing a pyrazole moiety with azo and hydrazo groups in the design of new antimicrobial agents.

Synthesis and Evaluation of Antioxidant Properties of 2-Substituted Quinazolin-4(3H)-ones

Quinazolinones represent an important scaffold in medicinal chemistry with diverse biological activities. Here, two series of 2-substituted quinazolin-4(3H)-ones were synthesized and evaluated for their antioxidant properties using three different methods, namely DPPH, ABTS and TEACCUPRAC, to obtain key information about the structure–antioxidant activity relationships of a diverse set of substituents at position 2 of the main quinazolinone scaffold. Regarding the antioxidant activity, ABTS and TEACCUPRAC assays were more sensitive and gave more reliable results than the DPPH assay. To obtain antioxidant activity of 2-phenylquinazolin-4(3H)-one, the presence of at least one hydroxyl group in addition to the methoxy substituent or the second hydroxyl on the phenyl ring in the ortho or para positions is required. An additional ethylene linker between quinazolinone ring and phenolic substituent, present in the second series (compounds 25a and 25b), leads to increased antioxidant activity. Furthermore, in addition to antioxidant activity, the derivatives with two hydroxyl groups in the ortho position on the phenyl ring exhibited metal-chelating properties. Our study represents a successful use of three different antioxidant activity evaluation methods to define 2-(2,3-dihydroxyphenyl)quinazolin-4(3H)-one 21e as a potent antioxidant with promising metal-chelating properties.

Crystal structure of 2-oxo-1,2-diphenylethyl diisopropylcarbamate

The title compound, C21H25NO3, crystallized as a racemic twin in the Sohnke space group P21. In the molecular structure of the title compound, both enantiomers show a highly similar conformation with the urethane function and the benzoyl group showing an almost perpendicular arrangement [the dihedral angle is 72.46 (8)° in the S-enantiomer and 76.21 (8)° in the R-enantiomer]. In the crystal structure, molecules of both enantiomers show infinite helical arrangements parallel to the b axis formed by weak C—H...O hydrogen bonds between the phenyl ring of the benzoyl group and the carbamate carbonyl group. In case of the R-enantiomer, this helix is additionally stabilized by a bifurcated hydrogen bond between the carbonyl function of the benzoyl group towards both phenyl groups of the molecule.

Cationic yet Stronger Donor: A Surprising Partner Effect and the Partner Strategy in Accelerating a Pincer-Co Catalyzed Nitrile Hydroboration Reaction

A strategy to tune the catalytic behavior of a organometallic catalysts rather than ligand engineering is suggested in this work, by computationally studying the effect of (18-crown-6)K+, W(CO)3 and W(PMe3)3 on the reactivity of a Pincer-Co catalyzed nitrile hydroboration reaction through π-coordination to the ligand aromatic ring. These extra additives, as called by the partners, binds the central phenyl ring of the ligand by either dispersion or chemical bonding. The electron-richness of the cobalt center is tuned by the partner, and follows the order (18-crown-6)K+ > W(PMe3)3 > no partner > W(CO)3. While the influence of covalent W-containing partners parallels the electron-richness of W, the non-covalent partner, (18-crown-6)K+, surprisingly increases the donor ability of the Pincer ligand, through polarization effect. All the elementary steps involved in the nitrile hydroboration reaction are influenced by the partner, and the overall barrier is lowered by a surprisingly large extent of 4.9 kcal/mol in the presence of (18-crown-6)K+, suggesting a charming partner effect to be explored by experimentalists that the reactivity of a catalyst can be consecutively tuned without ligand modification.