Halogen Substitution Research Articles

Structural comparison of five new halogenated dihydroquinoline-4(1H)-ones

Compounds with dihydroquinoline-4(1H)-one nuclei have been reported in the literature for being important in the development of medicines due to their broad spectrum of activities. In this way, the structural knowledge of this class becomes relevant for obtaining new materials with desired biological properties. This study presents the structural elucidation of five halogenated dihydroquinolines, as well as the discussion about the effect on the molecular conformation of the type and position of halogen atom on aromatic rings. Compounds I and IV differ in halogen substitution on 2-phenyl ring, while compounds III and V differ in halogen substitution on the benzylidene ring. Moreover, compound II has a para-substituted 2-phenyl ring in their molecular structure. The crystal packing of all five molecules is mainly ruled by C–H⋯O and C–H···halogen interactions that form dimers and chains. The shift in position and the kind of the halogen in ring C shows a starring role in the conformation of the studied compounds, and the packaging of these compounds is more susceptible to variations when the halogen position changes.

Synthesis and screening of (E)-3-(2-benzylidenehydrazinyl)-5,6-diphenyl-1,2,4-triazine analogs as novel dual inhibitors of α-amylase and α-glucosidase

(E)-3-(2-Benzylidenehydrazinyl)-5,6-diphenyl-1,2,4-triazines analogs 1–27 were synthesized by multi-step reaction scheme and subjected to in vitro inhibitory screening against α-amylase and α-glucosidase enzymes. Out of these twenty-seven synthetic analogs, ten compounds 14–17, 19, and 21–25 are structurally new. All compounds exhibited good to moderate inhibitory potential in terms of IC50 values ranging (IC50 = 13.02 ± 0.04–46.90 ± 0.05 µM) and (IC50 = 13.09 ± 0.08–46.44 ± 0.24 µM) in comparison to standard acarbose (IC50 = 12.94 ± 0.27 µM and 10.95 ± 0.08 µM), for α-amylase and α-glucosidase, respectively. Structure-activity relationship indicated that analogs with halogen substitution(s) were found more active as compared to compounds bearing other substituents. Kinetic studies on most active α-amylase and α-glucosidase inhibitors 5, 7, 9, 15, 24, and 27, suggested non-competitive and competitive types of inhibition mechanism for α-amylase and α-glucosidase, respectively. Molecular docking studies predicted the good protein-ligand interaction (PLI) profile with key interactions such as arene-arene, H-<, <-<, and <-H etc., against the corresponding targets.

SYNTHETIC METHODS, PROPERTIES AND APPLICATION OF CONDENSATION PRODUCTS OF 1,8-NAPHTHALIC ANHYDRIDES WITH 1,2-DIAMINES (A REVIEW)

The literary data concerning preparation methods and spectral properties of cyclocondensation products of 1,8-naphthalic anhydrides with aromatic and aliphatic 1,2-diamines and their use as luminescent materials have been summarized. The reaction of 1,8-naphthalic anhydrides with ortho-phenylenediamine results in the formation of 1,8-naphthoylene-1’,2’-benzimidazoles, which are widely used as materials for luminescent flaw detection, for synthesis of polymers with luminescent color, in organic light emitting diodes, as luminescent sensors for cations of various metals. Moreover, their cytotoxic activity is studied in relation to cells of various tumors. Acenaphthoquinone or 8-formyl-1-naphthoic acid can also be used as starting materials for synthesis of 1,8-naphthoylene-1’,2’-benzimidazoles. The spectral properties of 1,8-naphthoylene-1’,2’-benzimidazoles can be varied by the substituent introduction to naphthalene or/and phenyl moieties leading to luminescent materials with blue, green-yellow or red luminescence. Reaction of 4-substituted naphthalic anhydrides with o-phenylenediamine results in mixture of two constitutional isomers due to nonequivalence of two carbonyl groups in starting anhydride. The isomer ratio remains unchanged provided that syntheses are carried out under the same conditions, therefore the luminescent properties of such isomer mixtures are constant. 1,8-Naphthoylene-1’,2’-benzimidazoles with electron donating groups in positions 4 or 5 of naphthalene ring can be successfully obtained by nucleophilic aromatic substitution of halogen by amine or alcoholate. The introduction of electron donating substituents to positions 4 or 5 of naphthalene ring results in bathochromic shift of absorption and emission maxima compared to unsubstituted 1,8-naphthoylene-1’,2’-benzimidazole, corresponding shift is 10-20 nm larger for 5-isomer than for 4-isomer. There are few examples of applying amines other than o-phenylenediamine for cyclocondensation with naphthalic anhydrides, for instance naphthalene-2,3-diamine and ethylenediamine were used as starting materials.

Structural Assessment of Fluorine, Chlorine, Bromine, Iodine, and Hydroxide Substitutions in Lead Arsenate Apatites (Mimetites)–Pb5(AsO4)3X

Five lead-arsenate apatites (mimetites)-Pb5(AsO4)3X—where X denotes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and hydroxide (OH)—were synthesized via precipitation from aqueous solutions. The crystal structures were determined through Rietveld refinement of powder synchrotron X-ray data. All the compounds crystallized in the hexagonal class symmetry (space group P63/m). The Rietveld refinement indicated that mimetite-Cl, -Br, -I, and -OH had an anion deficiency at position X. Substitution of halogens in a mimetite structure brought about systematic changes in unit-cell parameters, interatomic distances, and metaprism twist angles φ, proportional to the substituted halogen’s ionic radius. Mimetite-OH did not follow the linear correlations determined within the series. Twist angle φ, a useful device for monitoring changes in apatite topology, ranged from 20.34° for mimetite-F to 11.42° for mimetite-I. The geometric method has been proposed for determining the diameter of hexagonal channels hosting halogens in apatites. A comparison of the results with halogenated pyromorphites showed similar systematic trends: the substitutions in mimetites have comparable effect on the interatomic distances as in their phosphorous analogues.

Halogen Substitution in Zero‐Dimensional Mixed Metal Halides toward Photoluminescence Modulation and Enhanced Quantum Yield

AbstractZero‐dimensional (0D) organic−inorganic hybrid metal halides haveunprecedented degrees of freedom for structural tunability and photoluminescence modulation. Here, the 0D isomorphic hybrid metal mixed halides (C9NH20)9Pb3Zn2Br19(1−x)Cl19x (x = 0–1) with continuous halogen contents control, exhibiting tunable emission and enhancement of photoluminescence quantum yield (PLQY) are reported. The competitive bromine to chlorine substitution process in (C9NH20)9Pb3Zn2Br19(1−x)Cl19x occurs first in [ZnBr4−xClx]2− tetrahedron before the [Pb3Br11−xClx]5− trimer. The increasing Cl content in samples from x = 0 to 1 results in an expected blue shift of emission peak from 565 to 516 nm, and meanwhile a strikingly room temperature PL quantum yield increase from 8% to 91%. Combined experimental characterizations and theoretical calculations indicate that the blue shift of interband transition energy is responsible for the emission peak shift. Moreover, with the increasing Cl content, the enhanced electron−phonon interaction and the weakened thermal‐assisted nonradiative recombination result in more efficient radiative transition channels and ultimately enhanced PLQY. The impact of halogen substitution on electronic structures and optical properties in 0D hybrid metal halides is emphasized in this work as a new strategy to promote the future development of new luminescent materials.

A2AgCrBr6 (A = K, Rb, Cs) and Cs2AgCrX6(X = Cl, I) Double Perovskites: A Transition-Metal-Based Semiconducting Material Series with Remarkable Optics.

With an interest to quest for transition metal-based halogenated double perovskites AB′B″X6 as high performance semiconducting materials for optoelectronics, this study theoretically examined the electronic structures, stability, electronic (density of states and band structures), transport (effective masses of charge carriers), and optical properties (dielectric function and absorption coefficients, etc.) of the series A2AgCrBr6 (A = K, Rb, Cs) using SCAN + rVV10. Our results showed that A2AgCrBr6 (A = Rb, Cs), but not K2AgCrBr6, has a stable perovskite structure, which was revealed using various traditionally recommended geometry-based indices. Despite this reservation, all the three systems were shown to have similar band structures, density of states, and carrier effective masses of conducting holes and electrons, as well as the nature of the real and imaginary parts of their dielectric function, absorption coefficient, refractive index, and photoconductivity spectra. The small changes observed in any specific property of the series A2AgCrBr6 were due to the changes in the lattice properties driven by alkali substitution at the A site. A comparison with the corresponding properties of Cs2AgCrX6 (X = Cl, I) suggested that halogen substitution at the X-site can not only significantly shift the position of the onset of optical absorption found of the dielectric function, absorption coefficient and refractive spectra of Cs2AgCrCl6 and Cs2AgCrI6 toward the high- and low-energy infrared regions, respectively; but that it is also responsible in modifying their stability, electronic, transport, and optical absorption preferences. The large value of the high frequency dielectric constants—together with the appreciable magnitude of absorption coefficients and refractive indices, small values of effective masses of conducting electrons and holes, and the indirect nature of the bandgap transitions, among others—suggested that cubic A2AgCrBr6 (A = Rb, Cs) and Cs2AgCrCl6 may likely be a set of optoelectronic materials for subsequent experimental characterizations.

Biosynthetic Plasticity Enables Production of Fluorinated Aurachins.

Enzyme promiscuity has important implications in the field of biocatalysis. In some cases, structural analogues of simple metabolic building blocks can be processed through entire pathways to give natural product derivatives that are not readily accessible by chemical means. In this study, we explored the plasticity of the aurachin biosynthesis pathway with regard to using fluoro‐ and chloroanthranilic acids, which are not abundant in the bacterial producers of these quinolone antibiotics. The incorporation rates of the tested precursor molecules disclosed a regiopreference for halogen substitution as well as steric limitations of enzymatic substrate tolerance. Three previously undescribed fluorinated aurachin derivatives were produced in preparative amounts by fermentation and structurally characterized. Furthermore, their antibacterial activities were evaluated in comparison to their natural congener aurachin D.

Biological macromolecule binding and anticancer activity of synthetic alkyne-containing L-phenylalanine derivatives.

Herein, we described the synthesis of two L-phenylalanines α-derivatized with a terminal alkyne moiety whose structures differed by phenyl ring halogen substitution (two o-Cl in 1 vs. one p-Br in 2) and investigated their effect on biological macromolecules and living cells. We explored their interaction with quadruplex DNA (G4 DNA), using tel26 and c-myc as models, and bovine serum albumin (BSA). By CD spectroscopy, we found that 1 caused minor tel26 secondary structure changes, leading also to a slight thermal stabilization of this hybrid antiparallel/parallel G4 structure, while the c-myc parallel topology remained essentially unchanged upon 1 binding. Other CD evidences showed the ability of 1 to bind BSA, while molecular docking studies suggested that the same molecule could be housed into the hydrophobic cavity between sub-domains IIA, IIB, and IIIA of the protein. Furthermore, preliminary aggregation studies, based on concentration-dependent spectroscopic experiments, suggested the ability of 1 to aggregate forming noncovalent polymeric systems in aqueous solution. Differently from 1, the bromine-modified compound was able to bind Cu(II) ion, likely with the formation of a CuL2 complex, as found by UV spectroscopy. Finally, cell tests excluded anycytotoxic effect of both compounds toward normal cells, but showed slight antiproliferative effects of 2 on PC3 cancerous cells at 24h, and of 1 on both T98G and MDA-MB-231 cancer cells at 48h.

Intramolecular Charge Transfer in 5-Halogen Cytidines Revealed by Femtosecond Time-Resolved Spectroscopy.

Ultraviolet radiation induced damage to DNA/RNA can lead to chemical modifications to the nucleosides, and understanding the excited states involved is the key to reveal the mechanism of those reactions. 5-Halogen cytidines are metabolized DNA/RNA nucleoside byproducts that exhibit very important biological functions in the process of nucleic acid methylation as well as DNA/RNA damage repairing. However, despite the accumulation of knowledge about their biological functions, the effects of halogen substitution on the excited states of canonical nucleoside have not received much attention. In this work, the excited-state dynamics of 5-fluorocytidine, 5-chlorocytidine, and 5-bromocytidine is investigated. Excitation at 295 nm results in a bifurcation event that leads to sub-picosecond decay to ground state and population of intramolecular charge transfer states which have several to tens of picosecond lifetimes. The results elucidate the general excited-state relaxation pathways in 5-halogen cytidines, and the intrinsic charge transfer state may affect the halogen bonding that stabilizes DNA and protein structures when 5-halogen cytidines are excited.

Strategic Halogen Substitution to Enable High‐Performance Small‐Molecule‐Based Tandem Solar Cell with over 15% Efficiency

AbstractSmall molecules have been recently highlighted as active materials owing to their facile synthesisis method, well‐defined molecular structure, and highly reproducible performance. In particular, optimizing bulk heterojunction (BHJ) morphologies is important to achieving high performance in solution‐processable small molecule solar cells (SM‐SCs). Herein, a series of benzodithiophene‐based active materials with different halogen atoms substituted at the end‐group, are reported, as well as how these halogen atoms affect the morphology of BHJ architectures through microstructure analyses. Materials with chlorine atoms show a well‐mixed morphology and interpenetrating networks when blended with [6,6]‐phenyl‐C71‐butyric acid methyl ester, facilitating effective charge transportation. This controlled morphology helps attain excellent performance with a power conversion efficiency (PCE) of 10.5% and a highest fill factor of 78.0% without additives. In addition, it can be applied to two‐terminal (2T)‐tandem solar cells, attaining an outstanding PCE of up to 15.1% with complementary absorption in the field of the 2T‐tandem solar cells introducing the SM‐SCs. These results suggest that tailoring interactions with halogen atoms is an effective way to control BHJ architectures, thereby achieving remarkable performance in SM‐SCs.

Comparative performance of TiO2-rGO photocatalyst in the degradation of dichloroacetic and perfluorooctanoic acids

Halogenated organic compounds are frequently characterized by their bioaccumulative nature, and long­term effects on human health. Their low biodegradability and their difficult removal by conventional technologies lead to their undesirable persistence in the environment. Titanium dioxide and reduced graphene oxide TiO2-rGO composites have shown promising results with enhanced photocatalytic degradation rates compared to bare TiO2 in the degradation of a good number of persistent pollutants. In this context, this work deepens on the influence of the type and number of halogen substitution on the photocatalytic degradation of halogenated organic compounds (HOCs). For the experimental analysis two HOCs, dichloroacetic acid (DCA) and perfluorooctanoic acid (PFOA), have been selected as both molecules differ in the type of halogen atoms, chlorine and fluorine, the number of halogen atoms, and in the length of the alkyl chain. The results showed that TiO2-rGO catalysts achieved a similar kinetic performance for the removal of the primary contaminant in terms of its degradation rate. Besides, TiO2-rGO composite successfully induced the release of all chlorine atoms from the DCA molecule, achieving its total mineralization. However, PFOA defluorination and mineralization rates were remarkably lower than its degradation rate. Although both contaminants released two halogen atoms step-by-step for the degradation of each molecule, PFOA dehalogenation was slowed down due to the generation of secondary products that retain fluorine. Therefore, we conclude that the composite photocatalysts showed a similar performance in terms of degradation rate of the primary contaminant independent on the length of the alkyl chain and on the number of halogen atoms, however, the mineralization and dehalogenation rates were strongly dependent on the number of halogen substituents and the length of the alkyl chain.

Halogen substitution regulates the phase transition temperature and band gap of semiconductor compounds.

(CH3CH2NH3)3BiX6 and (CH2ClCH2NH3)3BiX6 (X = Cl, Br) obtained by halogen substitution not only realize the adjustment of the phase transition in a relatively wide temperature range, but also optimize the semiconductor performance. This will promote the exploration and construction of semiconductor materials with tunable temperatures and lower band gaps.

Quantitative assessment of the nature of noncovalent interactions in N-substituted-5-(adamantan-1-yl)-1,3,4-thiadiazole-2-amines: insights from crystallographic and QTAIM analysis.

Three adamantane-1,3,4-thiadiazole hybrid derivatives namely; N-ethyl-5-(adamantan-1-yl)-1,3,4-thiadiazole-2-amine I, N-(4-fluorophenyl)-5-(adamantan-1-yl)-1,3,4-thiadiazole-2-amine II and (4-bromophenyl)-5-(adamantan-1-yl)-N-1,3,4-thiadiazole-2-amine III, have been synthesized and crystal structures have been determined at low temperature. The structures revealed that the orientation of the amino group is different in non-halogenated structures. Intra- and intermolecular interactions were characterized on the basis of the quantum theory of atoms-in-molecules (QTAIM) approach. Intermolecular interaction energies for different molecular pairs have been obtained using the PIXEL method. Hirshfeld surface analysis and 2D-fingerprint plots revealed that the relative contributions of different non-covalent interactions are comparable in compounds with halogen (Br and F) substitutions. Crystal structures of II and III show isostructural behaviour with 1D supramolecular constructs. In all three structures, the N–H⋯N hydrogen bond was found to be stronger among other noncovalent interactions. The H–H bonding showed a closed shell in nature and played significant roles in the stabilization of these crystal structures.

Singlet and triplet cyclonona‐3,5,7‐trienylidenes and their α, ά‐halogenated derivatives at DFT

AbstractSinglet and triplet boat‐shaped cyclonona‐3,5,7‐trienylidene (1H‐S and 1H‐T) and their corresponding α, ά‐tetrahalo derivatives (1F‐S, 1F‐T, 1Cl‐S, 1Cl‐T, 1Br‐S, 1Br‐T, 1I‐S, and 1I‐T) are compared at M06‐2X/AUG‐cc‐pVDZ, B3LYP/AUG‐cc‐pVTZ, and B3LYP/6‐311++G** levels of theory. Apart from 1H‐S which turns out as a transition state for having a negative force constant, the other structures appear as minima on their potential energy surfaces. 1H, 1Cl, and 1Br carbenes have triplet ground states, while 1F and 1I which initially take on a singlet multiplicity and eventually transform to a more stable intramolecular [1 + 2] cycloaddition product, and trans alkene, respectively. Except for 1H‐T and 1F‐T carbenes, the other triplet states emerge as allene isomer after optimization. We conclude that halogen substitution increases stability based on absolute value of singlet‐triplet energy separation (|ΔES‐T|), in the following order 1Br &lt; 1H ≤ 1Cl &lt; 1I &lt; 1F at B3LYP/AUG‐cc‐pVTZ, and 1Br &lt; 1Cl &lt; 1H &lt; 1I &lt; 1F at M06‐2X/AUG‐cc‐pVDZ. Nucleophilicity of the carbenic center is decreased due to higher electronegativity of substituted halogens. The scrutinized carbenes 1Cl‐S, 1Br‐S, and 1I‐S show higher nucleophilicity and higher electrophilicity than the synthesized common NHCs (2‐6). Hence, compared with 2‐6 carbenes, these halogenated carbenes exhibit ambiphilic character owing to the presence of a σ2‐orbital and vacant 2pπ‐orbital that makes them theoretically more susceptible for attacking an electrophile or a nucleophile.

Abstract C093: Substituted pteridinones as p90 ribosomal S6 protein kinase 2 (RSK2) inhibitors and their evaluation in acute myeloid leukemia

Abstract The activity of p90 ribosomal S6 kinase 2 (RSK2) has emerged as an attractive target for cancer therapy due to its role in the regulation of diverse cellular processes, such as cell transformation and proliferation and the maintenance of cancer stem cells (CSCs). Several pan-RSK inhibitors have been identified with BI-D1870 and the simple LJH685 and LJI308 analogs being the most selective, potent, and frequently used small molecules to identify the physiological substrates and functional roles for RSK in cells. However, these RSK inhibitors have poor PK profiles, display high clearance and a short plasma half-life and this has prevented their transition to clinical evaluation. Therefore, we designed and synthesized a series of pteridinones and pyrimidines to evaluate the structural features of BI-D1870 that are required for RSK2 inhibition, with the overall aim of developing a RSK inhibitor with improved drug-like properties. We have identified inhibitors of recombinant RSK2 activity, evaluated their target engagement in cells, and measured their effect on cell viability and cytotoxicity in the molm-13 acute myeloid leukemia (AML) cell line. The results of our initial structure-activity studies indicate that halogen substitutions on the 4-hydroxyanilino ring can greatly influence RSK inhibitory potency, elimination of C7 chirality does not appear to effect RSK inhibitory potency, removal of the N5-methyl maintains RSK inhibitory activity, and the N7-alkyl substitution is required for potent RSK inhibition. We have identified compounds that potently inhibit RSK2 activity in cells using the nanoBRET assay, and coupled with the results from our cellular viability and toxicity studies our data supports that RSK2 inhibition is independent from acute cytotoxicity in molm-13 cells. This finding was surprising as the RSKs phosphorylate a number of substrates involved in many diverse cellular processes critical for cell survival. Our studies have provided important structural information for the further development of RSK inhibitors and potential insights into structural modifications that may limit metabolism and incorporate isoform selectivity. Further studies are required to determine the impact of RSK inhibition in cancer cells as synergistic combination therapies may need to be identified. Alternatively, RSK inhibitors may be more therapeutically effective against specific cancer cell populations, such as in the elimination of CSCs. Citation Format: Kimberly Casalvieri, Christopher Matheson, Philip Reigan, Donald Backos. Substituted pteridinones as p90 ribosomal S6 protein kinase 2 (RSK2) inhibitors and their evaluation in acute myeloid leukemia [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C093. doi:10.1158/1535-7163.TARG-19-C093

Halogenation on terminal groups of ITIC based electron acceptors as an effective strategy for efficient polymer solar cells

Acceptor halogenation is an excellent modification method for modulating molecular energy levels, improving optical absorption, shortening the intermolecular packing distance thus ameliorating morphologies and achieving effective exciton dissociation and charge transfer of organic photovoltaic device. In this work, F, Cl and Br terminated ITIC small molecule acceptor (SMA) derivatives (IT-2F, IT-2Cl and IT-2Br) are designed and synthesized to compare the halogen substitution effect. Among these three acceptors, IT-2F based PSCs devices show the highest power conversion efficiencies (PCEs) around 12.08%, but Br terminated ITIC show downshifted LUMO energy level. Brominated ITIC show comparable PCEs with Cl and F terminated compound, and moreover chlorinated and brominated ITIC show low synthesis cost and easy purification than fluorinated materials, which may be favorable for future commercialization.

One-Dimensional Cadmium Thiocyanate Perovskite Ferroelastics Tuned by Halogen Substitution

Organic–inorganic hybrid molecular ferroelastics have gained widespread attention as a promising candidate for data storage, sensor, and mechanical switch applications. However, it remains a great ...

QSAR, Docking Study of Isatin Analogues as Anti-bacterial Agents for Design New Compounds

Computational chemistry is unique method in drug discovery which reduce cost. In this study 86 molecules containing isatin core were subjected to quantitative structure-activity relationship analysis and docking study to find the structure requirements for ligand binding. The structures were sketched and optimized in Hyperchem. The structural invariants used in this study were those obtained from whole molecular structures: by both hyperchem and dragon software (16 types of descriptors). Four chemometrics methods including MLR, FA-MLR, PCR and GA-PLS were employed to make connection between structural parameters and anticancer effects. MLR analysis explained the positive effect of the number of urea derivatives, thio urea, amide, thioamide, hydrazone, thiocarbohydrazone, nBnz with the halogen substitution on 5 position of isatin ring on the antimicrobial activity. It also shows nArCN, nPyridines have negative effects on the antimicrobial activity of studied compound.&#x0D; The FA-MLR describes the effect of 3D-MORSE and Galvez Topological charge descriptors and on antimicrobial activity of the studied compounds. The quality of PCRA equation is better than those derived from FA-MLR. A comparison between the different statistical methods employed revealed that GA-PLS represented superior results and it could explain and predict 73% and 68% of variances in the –LogMIC data, respectively. Comparison between QSAR and docking analysis revealed that by decreasing in number of ring and lipophilicity (also Logp) for design of new compounds can have better activity. Substitutions such as urea, thiourea, thiocarbohydrazone, benzhydrazide as on isatin ring, can cause better interaction with receptor.

Exploring the Influence of Halogen Coordination Effect of Stable Bimetallic MOFs on Oxygen Evolution Reaction.

The energy crisis and environmental pollution have forced scientists to explore alternative energy conversion and storage devices. The anodic reactions of these devices are all oxygen evolution reactions (OER), so the development of efficient OER electrocatalysts is of great significance. At the same time, understanding the reaction mechanism of OER is conducive to the rational design of efficient OER electrocatalysts. In general, catalytic active centers play a direct role in OER performance. In this paper, a series of stable bimetallic metal-organic frameworks (MOFs, named as Fe3 -Con -X2 , n=2, 3 and X=F, Cl, Br) with similar structure were synthesized by changing the halogen coordinated with the cobalt metal active center, aiming to investigate the influence of halogen substitution effect on OER performance. It was found that the OER activity of Fe3 -Co3 -F2 is much better than Fe3 -Co2 -Cl2 and Fe3 -Co2 -Br2 , indicating that the regulation of the electronegativity change of the coordination halogen atom can regulate the coordination electron structure of the metal active center, thereby achieving effective regulation of OER performance.

SYNTHESIS OF BENZO[ c ][1,7]NAPHTHYRIDINE DERIVATIVES

Reactivity of 2-methyl-6-phenylbenzo[c][1,7]naphthyridine in alkylation, oxidation, and electrophilic substitution reactions has been studied. The reaction of 2-methyl-6-phenylbenzo[c][1,7]naphthyridines with POCl3 yielded the previously unknown 4-chloro-2-methyl-6-phenylbenzo[c]-[1,7]naphthyridine. Its dehalogenation and substitution of halogen by nitrogen and sulfur nucleophiles were studied.