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This work deals with the synthesis, spectroscopic studies and catalytic evaluation of the novel chiral salen (L 1 H 2) and (L 2 H 2) ligands and their chiral boronate [ L 1 (B 1-4) ] and [ L 2 (B 1-4)] complexes. Initially, the reaction of 5-azidomethyl salicylaldehyde and (R)-(−)-2-amino-1-butanol in absolute ethanol afforded a new chiral salen ligand (L 1 H 2). Then, a novel chiral salen ligand (L 2 H 2) have been prepared from chiral salen ligand (L 1 H 2) for the synthesis of boronate [ L 2 (B 1-4)] complexes through click reaction approach under ambient conditions. The reaction of chiral salen (L 1 H 2) and (L 2 H 2) ligands with various boronic acids afforded a new tetra-coordinated mononuclear chiral boronate [ L 1 (B 1-4) ] and [ L 2 (B 1-4)] complexes. All the compounds are remarkably stable crystalline solids and were obtained in good yields. For the full characterization of newly synthesized chiral salen ligands and their boronate complexes, the FT-IR, UV–Vis, NMR (1H, 13C, and 11B), LC-MS, and elemental analysis techniques have been used. The well-shaped chiral boronate compounds were investigated as catalyst for the asymmetric transfer hydrogenation (ATH) of aromatic ketones under appropriate settings. Particularly, it was proved that the ferrocene-based boronate compounds can afford an efficient catalytic conversion compared to the other boronate complexes in the asymmetric transfer hydrogenation catalytic studies. Image 1 • The new chiral boronate-catalysts were prepared and fully characterized. • The various spectroscopic methods were used for characterization. • The chiral boronate catalysts was used for the asymmetric transfer hydrogenation. • The chiral catalyst [L 2 B 1 ] afforded good enantio-selectivities in the asymmetric transfer hydrogenation. [ABSTRACT FROM AUTHOR]

A family of hemi-salen (L1H–L6H) and hemi-salan (L1aH–L2aH) ligands-based N,O-chelated binuclear boron-fluoride [Ln(BF2)2] (n = L1–L6 or L1a–L2a) complexes have been prepared and characterized by a variety of spectroscopic techniques (1H, 13C and 19F NMR, FT-IR, UV-Vis, LC-MS, and fluorescence spectra) and elemental analysis. All of the binuclear boron-fluoride complexes exhibit strong absorption bands due to S0→S1 transitions and strong fluorescence properties were observed at room temperature in the solution. The binuclear boron complexes containing two naphthyl groups are significantly red-shifted in comparison with the other binuclear boron-fluoride complexes. After the structures are characterized, these hemi-salen and salan ligand-based N, O-chelated binuclear boron-fluoride complexes were utilized to the transfer hydrogenation of the different acetophenone derivatives conversion to 1-phenylethanol derivatives as catalysts. [ABSTRACT FROM AUTHOR]

Abstract In the present work, firstly a novel monoxime (1) and unsymmetric dioxime ligand (LH 2) (2) derived from 4-(4-hydroxyphenyl)-2-butanone as ketone was prepared under optimum conditions. Then, the cobaloxime complexes [(LH) 2 ClCoB] (B = neutral base: 4-DAP = 4-(dimethylamino)pyridine, 4-HP = 4-hydroxypyridine, 4-CP = 4-chloropyridine, 4-MP = 4-methylpyridine, 4-EP = 4-ethylpyridine, 4-TBP = 4- tert -butylpyridine and P = pyridine) (3–9) with respect to varied axial groups were synthesized in a two-necked round-bottom reaction flask by direct contact of dioxime ligand (2) , and different neutral base without special requirement of any additional chemical process. The prepared dioxime ligand (2) and its cobaloxime complexes (3–9) were characterized by means of NMR, FT-IR, UV–Vis and LC-MS spectroscopy, melting point and magnetic susceptibility measurements as well as elemental analysis. It is noteworthy that the coordination chemistry of this cobaloxime complexes is versatile, which is closely related to the nature of the unsymmetric dioxime ligand (2) derived from 4-(4-hydroxyphenyl)-2-butanone, as indicated by the results of the corresponding spectroscopic studies. Also, the spectroscopic results demonstrated that the proposed cobaloxime complexes are a six-coordinated species and octahedral geometry. Graphical abstract Image 1 Highlights • The different cobaloximes were prepared and fully characterized. • The various spectroscopic methods were used for characterization. • The cobaloxime complexes are a six-coordinated species and octahedral geometry. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel double and single cobaloxime salts were successfully synthesized. • The spectroscopic properties of cobaloxime salts were performed using spectral techniques. • The cobaloxime salts have been used as a catalyst for the green synthesis of cyclic under solvent-free. • The best conversion was performed in the presence of a catalyst (6) and DMAP as a co-catalyst, with a 98% yield and 99% selectivity. Cobalt(III)-based catalysts for CO 2 fixation are widely applied for the synthesis of cyclic carbonates from epoxides and CO 2 under suitable and solvent-free conditions. Inspired by the enhancing catalyst strategy for highly efficient CO 2 conversion into useful products, here we show that the cobaloximes (1 – 3) and corresponding to different double cobaloxime salts (4 – 6) , and their single salts with simple counterions (7 – 9) were prepared and evaluated as an efficient catalyst for the coupling of CO 2 and epoxides into cyclic carbonates. The structure of synthesized target cobaloximes was characterized using a combination of 1H, 13C, and 11B NMR spectra, FT-IR spectra, UV–Vis spectra, LC-MS/MS spectrometers, melting point, and elemental analysis techniques. Although the prepared cobaloxime-based catalytic systems were studied in a wide range of epoxide substrates, the highest catalytic activity was observed in the conversion of epichlorohydrin under suitable conditions. After seeing highly efficient catalytic conversion and selectivity of the newly synthesized cobaloximes (1 – 3) and different cobaloxime-based double complex salts (4 – 9) , the effect of epoxide, base, reaction time, temperature, and CO 2 pressure was investigated for these catalysts. The best conversion was performed in the presence of a catalyst (6) (the double cobaloxime salt bearing 4- t -butyl) and DMAP as a co-catalyst, with a 98% yield and 99% selectivities. [ABSTRACT FROM AUTHOR]

A novel class of tricoordinate dioxaborinane compounds, which have the general formula [B 1 (L 1–5 )] and [B 2 (L 1–5 )] , were designed and synthesized by the corresponding catechol-type ligands (L 1 –L 5 ) at ambient temperature. All the new compounds were fully characterized by NMR ( 1 H, 13 C, and 11 B), FT-IR, UV–vis, LC-MS spectroscopy, and melting point analysis and microanalysis. The dioxaborinane [B 1 (L 1–5 )] and [B 2 (L 1–5 )] compounds were investigated as catalyst for the transfer hydrogenation of various ketones under suitable conditions. Particularly, it was proved that the ferrocene-based dioxaborinane [B 1 (L 1–5 )] molecules can afford an efficient catalytic conversion compared to corresponding 3,5-bis(trifluoromethyl)phenyl-based [B 2 (L 1–5 )] dioxaborinanes in transfer hydrogenation catalytic studies. [ABSTRACT FROM AUTHOR]

A series of cobaloxime complexes (1-6) and corresponding to positively charged phosphonium linked cobaloximes (called cobaloximes-PCPL) (1a-6a) have been prepared in high yields and characterized by means of NMR ( 1 H, 13 C, and 31 P) spectra, FT-IR spectra, UV–Vis spectra, mass spectra, melting point as well as elemental analysis. Following a full characterization, the study of spectroscopic properties of these novels cobaloximes/cobaloximes-PCPL compounds was done in detail. Under optimized reaction conditions, these novel cobaloximes (1-6) and cobaloximes-PCPL (1a-6a) were applied to the as a molecular catalyst for the cycloaddition of epoxides with CO 2 without organic solvent. In a combination with (4-bromo butyl)triphenylphosphonium bromide (BTP) and cobaloxime compounds, namely cobaloximes-PCPL were identified as highly active catalysts for the formation of cyclic carbonates compared to previously reported cobaloximes catalysts by our groups. As an axial group bounding to the Co(III) center of cobaloximes-PCPL, (BTP) was barely revealed that it has an effect on catalyst activities. Also, a systematic investigation of reaction parameter effects such as temperature, time and pressure was done. [ABSTRACT FROM AUTHOR]

[Display omitted] • The boronate ester modified Fe 3 O 4 @APTES-B MNPs were prepared. • The spectroscopic properties and characterization were established by different spectral tools. • The target Fe 3 O 4 @APTES-B 1,2 MNPs are in nanosize since crystal sizes are < 100 nm. • The antioxidant, antimicrobial, and DNA binding activities of all compounds were tested. • Some compounds have been shown to have strong DNA binding activity. We have designed two novel magnetite targeting biological agents (Fe 3 O 4 @APTES-B (1,2)) with a core of Fe 3 O 4 and a shell made of boronate esters (APTES-B) to improve the biological effectiveness of magnetite Fe 3 O 4 nanoparticles (MNPs). Initially, two boronate esters (B 1) and (B 2) have been prepared by 3,4-dihydroxybenzaldehyde and phenylboronic acid and/or butylboronic acid using a Dean-Stark apparatus to remove the water formed during the esterification reactions. Then, the APTES-B 1,2 compounds have been synthesized via boronate esters and APTES in the presence of 1–2 drops of formic acid as catalyst. Finally, magnetite Fe 3 O 4 NPs were added to APTES-B 1,2 compounds to afford boronate ester modified magnetite iron nanoparticles (Fe 3 O 4 @APTES-B 1,2) at ambient temperature, respectively. The boronate esters (B 1) and (B 2) , APTES-B 1,2 compounds, and boronate ester modified magnetite iron nanoparticles (Fe 3 O 4 @APTES-B 1,2) were characterized using a combination of NMR (1H, 13C, and 11B), FT-IR, UV–Vis, LC-MS/MS, elemental analysis (CHN), XRD, SEM-EDX, EDX mapping, BET, and TG-DTA). Then, the antioxidant, antimicrobial and DNA binding activities of newly synthesized target compounds were tested. These results suggest that all compounds are also one of the propitious drug candidates and are worthy of further investigation. [ABSTRACT FROM AUTHOR]

A new series of Schiff base ligands (L 1 –L 3 ) and their corresponding fluorine/phenyl boron hybrid complexes [L n BF 2 ] and [L n BPh 2 ] ( n = 1, 2 or 3) have been synthesized and well characterized by both analytical and spectroscopic methods. The Schiff base ligands and their corresponding fluorine/phenyl boron hybrid complexes have been characterized by NMR ( 1 H, 13 C and 19 F), FT-IR, UV–Vis, LC–MS, and fluorescence spectroscopy as well as melting point and elemental analysis. The fluorescence efficiencies of phenyl chelate complexes are greatly red-shifted compared to those of the fluorine chelate analogs based on the same ligands, presumably due to the large steric hindrance and hard π → π ∗ transition of the diphenyl boron chelation, which can effectively prevent molecular aggregation. The boron hybrid complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. The catalytic studies showed that boron hybrid complexes are good catalytic precursors for transfer hydrogenation of aromatic ketones in 0.1 M iso -PrOH solution. Also, we have found that both steric and electronic factors have a significant impact on the catalytic properties of this class of molecules. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis and characterization of a new series of synthesized mono- and trinuclear cobaloxime/organocobaloximes from ketone that act as catalysts for cyclic carbonate synthesis from CO2 and epoxides under appropriate conditions (2 h, 100 °C and 1.6 MPa pressure). These reactions were carried out with and without co-catalyst, namely, 4-dimethylaminopyridine (DMAP), pyridine (py), triethyl amine (NEt3) or triphenyl phosphine (PPh3). In the catalytic experiments, the 4-dimethylaminopyridine (DMAP) was used as co-catalyst, since the DMAP was a more active base with higher yield compared to other Lewis bases. In addition, various factors influencing the cycloaddition reaction, such as co-catalyst, temperature, CO2 pressure and reaction time, were investigated. A dioxime ligand (LH2) (1) was obtained in two steps from 4-methylpropiophenone as ketone. Reaction of CoCl2.6H2O with the dioxime ligand (LH2) (1) and 4-tertbutyl pyridine afforded six-coordinate mononuclear cobaloxime or organocobaloxime (2-3) complexes. The mononuclear cobaloxime or organocobaloxime (2-3) complexes were used as precursors for building trinuclear cobaloximes or organocobaloxime (4-11) complexes. All compounds were fully characterized by ¹H and 13C NMR spectra, FT-IR spectra, UV--Vis spectra, molar conductivity measurements, melting point measurements, magnetic susceptibility measurements, and LC-MS spectroscopic studies as well as by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

The new cobaloxime (1), organocobaloxime (2), and their intramolecular hydrogen (O–H?O) bridges replaced by Cu(II)-containing multinuclear cobaloximes (3–10) were synthesized and characterized by elemental analysis,1H and13C NMR spectra, FT-IR spectra, UV–vis spectra, LC-MS spectra, molar conductivity measurements, melting point measurements, and magnetic susceptibility measurements. Their electrochemical properties were investigated using cyclic voltammetric techniques in DMSO solution. The cobaloxime or organocobaloxime (1,2) were used as precursors, replacing intramolecular O–H?O bridges, forming multinuclear complexes (3–10). Then, these compounds were used as homogeneous catalysts for cyclic carbonate synthesis from carbon dioxide (CO2) and epoxides. In the catalytic experiments, dimethyl amino pyridine (DMAP) was used as co-catalyst, since DMAP was a more active base with higher yield compared to other Lewis bases. It is not necessary to use solvent according to catalytic test results, important in green chemistry. In this paper, the new cobaloxime (1), organocobaloxime (2) and multinuclear cobaloximes (3–10) were synthesized and characterized. These compounds were used as homogeneous catalysts for cyclic carbonate synthesis from carbon dioxide (CO2) and epoxides. [ABSTRACT FROM AUTHOR]

Highlights: [•] The three type of cobaloximes have been synthesized and characterized. [•] The cobaloximes were used for insertion of carbon dioxide into epoxides. [•] 4-(Dimethylamino)pyridine (DMAP) was used as a co-catalyst. [•] Organodicobaloxime displayed the highest catalytic efficiency. [•] Good activity and selectivity were obtained with epichlorohydrin. [ABSTRACT FROM AUTHOR]

[Display omitted] • The trigonal planar or tetrahedral catechol boronate ester catalysts were reported. • Structural characterization was established by various spectroscopic techniques. • Catalytic efficiency of all boronate esters was tested in the hydrogen transfer reaction of ketones. • Among the boronate esters studied, (B 4) and (B 4 N) are the most active organocatalysts. • The catechol boronate esters are suitable candidate in the industrial applications as green catalysts. A series of new structurally related catechol boronate esters enabled by N → B dative bond of general composition (B 1 -B 4) and (B 1 N-B 4 N) were designed and synthesized for the transfer hydrogenation of various ketones, as catalysts. The structures of the synthesized trigonal-planar and tetrahedral catechol boronate esters forming dative bonds with neutral base were well-elucidated by NMR (1H, 13C, and 11B), FT-IR, UV–Vis, fluorescence, and LC-MS/MS spectroscopy, melting point and microanalysis. With the development of a more active and stable catalytic system for transfer hydrogenation of ketones in mind, all catechol boronate esters were tested as catalysts for the transfer hydrogenation of aromatic ketones, showing good activity in this reaction. Particularly, it was proved that the mononuclear molecules can afford an efficient catalytic conversion compared to the corresponding dinuclear boronate esters in transfer hydrogenation catalytic studies. Among the catalysts, (B 4) and (B 4 N) are the most active catalysts and catalytic activity of (B 4) was generally much higher in the studied hydrogen transfer reactions than that of (B 4 N) under mild conditions in iso PrOH. This clearly suggests that catechol boronate esters are also one of the propitious catalyst candidates and are worthy of further investigations. [ABSTRACT FROM AUTHOR]

Highlights: [•] The two ligand and its mononuclear Cu(II) complexes have been synthesized. [•] The Cu(II) complexes were synthesized for the coupling of carbon dioxide and epoxide. [•] Dimethylamino pyridine (DMAP) was used as co-catalyst. [•] A high selective conversion rate was obtained using catalyst and epichlorohydrine as the substrate. [Copyright &y& Elsevier]

The sterically hindered salicylaldimine ligands N,N′-(1,5-diaminonaphthalene)-3,5-but2-salicylaldimine (L1), N,N′-(2,7-diaminofluaren)-3,5-but2-salicylaldimine (L2) and N,N′-(1,8-diaminonaphthaline)-3,5-but2-salicylaldimine (L3) have been synthesised by the condensation of 1,5-diaminonaphthalene, 2,7-diaminofluarene, and 1,8-diaminonaphthaline with 3,5-di-tert-butylsalicylaldehyde, respectively. Dinuclear M(II) complexes of L1 and L2 and mononuclear M(II) complexes of L3 have been prepared using Cu(II), Ni(II), Co(II), and Mn(II) salts and characterised. The synthesised sterically-hindered, salen-type complexes were tested as catalysts for the formation of cyclic carbonates from CO2 and liquid epoxides (propylene oxide, epichlorohydrine, 1,2-epoxybutane and styrene oxide), which served as both reactant and solvent. Ligand structure and the type of metal centre have a marked influence on the catalytic activity. Mn(II) complexes showed the highest catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of the salicylaldimine ligands (L1H, L2H, L3H, L4H and L5H) with palladium(II) acetate in absolute ethanol gave the orthopalladation dinuclear [Pd(L1)(μ-OAc)]2, [Pd(L2)(μ-OAc)]2 and mononuclear [Pd(L3)2] with the tetradentate ligands [N, C, O] or [N, O] moiety. The ligands L1H and L2H are coordinated through the imine nitrogen and aromatic ortho carbon atoms, whereas the ligand L3H coordinated through the imine nitrogen and phenolic oxygens atoms. The Pd(II) complexes have a square-planar structure and were found to be effective catalysts for the hydrogenation of both nitrobenzene and cyclohexene. These metal complexes were also tested as catalysts in Suzuki–Miyaura coupling of aryl bromide in the presence of K2CO3. The catalytic studies showed that the introduction of different groups on the salicyl ring of the molecules effected the catalytic activity towards hydrogenation of nitrobenzene and cyclohexene in DMF at 25 and 45°C. The Pd(II) complexes easily prepared from cheap materials could be used as versatile and efficient catalysts for different C–C coupling reactions (Suzuki–Miyaura reactions). The structure of ligands and their complexes was characterized by UV–Vis, FT-IR, 1H and 13C NMR, elemental analysis, molar conductivity, as well as by electrochemical techniques. [Copyright &y& Elsevier]

The novel vic-dioxime ligand containing the 4-amino-1-benzyl piperidine group, N,N'-(4-amino-1-benzyl piperidine)-glyoxime, (LH2) has been prepared from 4-amino-1-benzyl piperidine with anti-dichloroglyoxime at -15°C in absolute THF. Mononuclear NiII metal complex has been obtained with 1 : 2 metal/ligand ratio. The NiII complex of this ligand is proposed to be square planar geometry. IR spectra show that the ligand acts in a tetradentate manner and coordinates N4 donor groups of LH2 to NiII ion. The detection of H-bonding (O-HߪO) in the [Ni(LH)2] (1) metal complex by IR spectra supported the square-planar MN4 coordination of mononuclear complex. The disappearance of H-bonding (O-HߪO) in the [Ni(L)2(BPh2)2] (2) complex shows that the BPh2+-capped groups (BPh2+ cation formed BPh4 anion) attaches to the main oxime core. MN4 coordination of the [Ni(LH)2] (1) and [Ni(L)2(BPh2)2] (2) metal complexes were also determined by ¹H-NMR spectroscopy. In the trinuclear CuII-NiII-CuII metal complexes, the NiII ion centered into the main oxime core by the coordination of the imino groups while the two CuII ions coordinate dianionic oxygen donors of the oxime groups and linked to the ligands of 1,10-phenanthroline, 2,2'-bipyridine, and 4,4'-bipyridine. The ligand and their mono and trinuclear metal complexes were characterized by elemental analyses, FT-IR, UV-Vis, ¹H and 13C-NMR spectra, magnetic susceptibility measurements, molar conductivity, cyclic voltammetry, mass spectra and X-ray powder techniques. The cyclic voltammetric results show that the cathodic peak potential of [Ni(L)2(BPh2)2] shifted toward more negative value compared to that of [Ni(LH)2], probably due to a decreasing effect of back donation of metal-oxime moieties as a result of the BPh2+ -bridged complex formation. Also, the formation of the trinuclear CuII-NiII-CuII metal complexes caused considerable changes on the CV behaviour of mononuclear [Ni(LH)2] (1) complex. The spectroelectrochemical study of [Ni(L)2(BPh2)2] (2) showed distinctive spectral changes that the intensity of the band (χ = at 364 nm, assigned to n → π* transitions) decreased and a new broad band in low intensity about 460 nm appeared as a result of the reduction of the nickel centered in the oxime core. [ABSTRACT FROM AUTHOR]

Abstract: Five new metal complexes [Pd(LH)2] (1), [Pd(L)2Ru2(bpy)4](ClO4)2 (2), [Pd(L)2Ru2(phen)4](ClO4)2 (3), [Pd(L)2Ru2(dafo)4](ClO4)2 (4) and [Pd(L)2Ru2(dcbpy)4](ClO4)2 (5), (where, L=ligand, bpy=2,2′-bipyridine, phen=1,10-phenantroline, dafo=4,5-diazafluoren-9-one and dcbpy=3,3′-dicarboxy-2,2′-bipyridine) have been isolated and characterized by UV–VIS, FT-IR, 1H NMR, magnetic susceptibility measurements, elemental analysis, molar conductivity, X-ray powder techniques, thermal analyses and their morphology studied by SEM measurements. IR spectra show that the ligand acts in a tetradentate manner and coordinates N4 donor groups of LH2 to PdII ion. The disappereance of H-bonding (O−H···O) in the trinuclear RuII–PdII–RuII metal complexes, the RuII ion centered into the main oxime core by the coordination of the imino groups while the two RuII ions coordinate dianionic oxygen donors of the oxime groups and linked to the ligands of bpy, phen, dafo and dbpy. The X-powder results show that 1 metal complex is indicating crystalline nature, not amorphous nature. Whereas, the X-ray powder pattern of the ligand (LH2) with 2, 3, 4 and 5 exhibited only broad humps, indicating its amorphous nature. The catalytic activity of three different complexes were tested in the Suzuki coupling reaction. The 1, 4 and 5 metal complexes catalyse Suzuki coupling reaction between phenylboronic acid and arylbromides affording biphenyls. Also, the thermal results shown that the most stable complex is 1 compound while the less stable is 4 compound. [Copyright &y& Elsevier]

The synthesis, spectroscopic, and redox properties of some metal complexes with three novel vic-dioxime ligands, N-(1-(2-aminoethyl)piperazine)-phenylglyoxime (L1H2), N-(1-(2-aminoethyl)piperazine)-glyoxime (L2H2), and N,N'-bis(1-(2-aminoethyl)piperazine)-glyoxime (L3H2)], prepared from different glyoxime and 1-(2-aminoethyl)piperazine are reported. The structure of these vic-dioximes have been determined as the anti-form according to 1H NMR, 13C NMR, and FT-IR data. The metal to ligand ratios of Co(II), Ni(II), and Cu(II) complexes were found to be 1 : 2. The Cu(II) complexes of these ligands are proposed to be square planar and Ni(II) complexes of these ligands are proposed to be square planar or octahedral, while the Co(II) complexes are proposed to be octahedral with water molecules as axial ligands. Ni(II), Co(II), and Cu(II) metal complexes are non-electrolytes as shown by their molar conductivities (ΛM) in DMF (dimethyl formamide) at 10-3 M. The structure of ligands and their complexes is proposed from elemental analysis, FT-IR, UV-VIS, 1H NMR, 13C NMR, magnetic susceptibility measurements, and molar conductivity measurements. The cyclic voltammetric measurements of the mononuclear complexes provide an understanding of the electrochemical behaviour of the reduced or oxidized species in DMSO solution. [ABSTRACT FROM AUTHOR]

• The novel boronate esters (1-8) were designed and characterized. • The elemental analysis, NMR, FT-IR, UV-Vis, fluorescence spectra, and LC-MS/MS were used for characterization of boronate esters. • The quantum yields (Φ) for boronate esters were calculated in C 2 H 5 OH solution • The boronate esters are tested as antimicrobial and antioxidant agents. • Some boronate esters showed better activity than Trx and Prg standards. Boron compounds are among the most widely used disinfectant agents due to their broad-spectrum antimicrobial and antioxidant activity. However, it cannot be said that the antimicrobial properties of boronate esters or 4,4′-bipyridine (4,4′-bpy) linker bioactive macrocycle boronate esters have been not fully studied.In this context, we present the synthesis of 4,4′-bipyridine linker bioactive macrocycle boronate esters with a B←N host, which could efficiently decrease the cytotoxicity toward various bacteria. The newly synthesized bioactive macrocycle boronate esters adducted 4,4′-bipyridine with a B←N host for antimicrobial agents were characterized using melting point, elemental analysis, NMR (1H, 13C, and 11B) spectra, FT-IR spectra, UV-Vis spectra, fluorescence spectra, and LC-MS/MS spectrometry. According to the antimicrobial activity results, it was determined that the boron compounds showing the best activity were (1), (5), and (6). When evaluated in general, it was determined that these boron compounds exhibited higher activity than streptomycin, cefazolin, and chloramphenicol antibiotics. Also, antioxidant studies show that boronate esters (2), (3), (4), and (7) displayed activity very close to standards, (1), (5), (6) and (8) showed better activity than Trx and Prg standards. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • New eco-friendly and metal-free imidazolium-organoboroncatalysts were designed and prepared. • Different techniques were used for the characterization of the imidazolium-organoboroncatalysts. • CO 2 fixation strategy is crucial for global warming, climate change and a sustainable future. • Imidazolium-organoboroncatalysts have been applied to synthesize cyclic carbonates from epoxide and CO 2. • CO 2 utilization in an excellent 97% yield with 98.9% selectivity confirms the potential for industrial applications. Organoboron compounds that are available in industrial and scientific research were investigated as organocatalysts for the coupling reaction of CO 2 into cyclic carbonates as fine chemicals in solvent-free and under sustainable green atmospheric and high-pressure conditions (1 atm and 1.6 MPa, 100 °C, 2 h). This work synthesized a series of imidazolium-organoboron catalysts (IBC 1 -IBC 8) using the eco-friendly and metal-free methodology and characterized by various analysis techniques. These techniques were NMR (1H, 13C, and 11B), UV–Vis, FT-IR, Mass spectrometry, C/H/N analysis, and melting point measurement together with thermal gravimetric analysis (TGA-DTA), respectively. After that, the Lewis acidity of the synthesized imidazolium-organoboron catalysts, which is important for catalytic CO 2 conversion studies, was investigated by the traditional Gutmann-Beckett test, and the Lewis acidity order of the target compounds was found at range 54.96–50.36 ppm. In the presence of 0.1 mol% imidazolium-organoboron catalyst (IBC 8) and 0.2 mol% DMAP as co-catalyst, 4-chloromethyl-1,3-dioxalan-2-one was obtained as cyclic carbonate from epichlorohydrin in 44.9 % yield and 97.6 % selectivity (1 atm and 100 °C) and in an excellent 97 % yield with 98.9 % selectivity (1.6 MPa and 100 °C) in 2 h without any solvents. After the imidazolium-organoboron catalyst (IBC 8) showed efficient catalytic conversion and high selectivity, the effect of different parameters, including the effect of substrate, Lewis acid-base, reaction time, reaction temperature, CO 2 pressure, and catalyst amount, was studied for this catalyst. According to the obtained catalytic conversion results, it was also determined that the optimum Cat./ECH ratio for CO 2 cycloaddition reactions is 1/1000. [ABSTRACT FROM AUTHOR]

• The new chiral boron complexes were prepared with high yield. • The various spectroscopic methods were used for compounds characterization. • The electrochemical properties were examined by CV. • Chiral (LB 2) complex had a much lower LUMO energy level. • Chiral boron complex (LB 2) showed the highest activity against all bacterial strains. • The antibacterial activity shows that nearly in the range of values for commercial antibacterial drugs. A new class of low-cost, easily-synthesizable and modifiable chiral amine bis(phenolate) ligand (L), its chiral boron complex (LB), and five different salen groups (1-(3-Aminopropyl) imidazole (LB 1) , N,N -Diethyl- p -phenylenediamine (LB 2) , 2-Picolylamine (LB 3) , 4′-Aminoacetophenone (LB 4), and 4-Amino-2,2,6,6-tetramethyl piperidine (LB 5)) containing chiral boron complexes were synthesized in this study. These newly synthesized chiral compounds were fully characterized by 1H and 13C NMR, FT-IR, UV–Vis, and LC-MS/MS spectroscopy, melting point, elemental analysis, and cyclic voltammetry techniques. The in vitro antibacterial activity of the synthesized different chiral boron complexes was tested against four pathogenic bacteria strains using the resazurin-based broth microdilution method, and the MIC values of each boron complex were determined. Based on the overall results, the N, N -Diethyl- p -phenylenediamine group containing chiral boron complex (LB 2) showed the highest activity against all bacterial strains, with the lowest MIC value of 4 µg/mL which is nearly in the range of values for commercial antibacterial drugs. [ABSTRACT FROM AUTHOR]

A new class of cheap, easily-synthesizable and modifiable boronate esters (B 1 –B 3) and their corresponding N -Heterocyclic Carbene (NHC)-stabilized boronate esters (B 4 –B 6) have been synthesized for the first time under toluene reflux using a Dean-Stark apparatus to remove the water by-product. All these newly synthesized boronate compounds were characterized using elemental analysis, and their probable structures were proposed based on 1H, 13C and, 11B NMR, FT-IR, UV–Vis spectral results and LC-MS/MS spectrometry. Antimicrobial activities of the boronate esters (B 1 –B 3) and their corresponding N -Heterocyclic Carbene (NHC)-stabilized boronate esters (B 4 –B 6) were investigated against 7 bacteria and 3 fungi. The boronate ester (B 1) showed the best antimicrobial activity. Besides, boronate ester (B 1) with (NHC)-stabilized boronate esters (B 5 and B 6) showed better antibacterial activity than antibiotics drugs. It has been observed that the (NHC)-stabilized boronate ester (B 5) removes the scavenging effect of H 2 O 2 +DMSO and stabilizes plasmid DNA at the highest rate when applied alone. Addition, the boronate esters (B 1 –B 3) and their corresponding N -Heterocyclic Carbene (NHC)-stabilized boronate esters (B 4 –B 6) have been tested for the radical scavenging activity of antioxidants. They have meaningful antioxidant activity compared to reference compounds. The results show that 100 μL of the boronate esters had low activity according to standards when DPPH radical removal activities were compared to standards. Image 1 • The novel boronate esters were prepared and fully characterized. • The various spectroscopic methods were used for characterization. • The boronate esters showed the best antimicrobial activity. • Some boronate esters showed better antibacterial activity than antibiotics drugs. [ABSTRACT FROM AUTHOR]

The sulfonamide compound, 4-[(2-hydroxy-3-methylbenzylidene)amino]benzenesulfonamide was synthesized and grown as a high quality single crystal by the slow evaporation solution growth technique. The structure of the compound was characterized by FT-IR, 1 H and 13 C NMR, UV–Vis and X-ray single crystal techniques. The compound crystallizes in the monoclinic space group Cc with a = 4.9690 (4) Å, b = 29.3068 (14) Å, c = 9.4490 (8) Å, and β = 97.174 (6)°, and Z = 4 in the unit cell. Density functional theory (DFT) calculations were carried out for the title compound by utilizing DFT level of theory using B3LYP/6-311++G(d,p) as basis set. The theoretical vibrational frequencies, 1 H and 13 C NMR chemical shifts, absorption wavelengths and optimized geometric parameters such as bond lengths and bond angles were calculated by using quantum chemical methods. In addition, DFT calculations of the title compound, Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO), Frontier Molecular Orbital (FMO) analysis, thermodynamic properties, dipole moments, and HOMO–LUMO energy were also computed. The calculated results show that the optimized geometry can well reproduce the crystal structure parameters, and the theoretical vibrational frequencies, 1 H and 13 C NMR chemical shifts and absorption wavelengths show good agreement with experimental values of the molecule. [ABSTRACT FROM AUTHOR]