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Schematic diagrams of the aromatic heterocyclic molecules with each one containing one carbon substituted with a boron.
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Aromatic heterocyclic molecules play an important role in synthetic organic chemistry due to their wide range of reactivity. Because of the aromatic property, they have less tendency to accept electron form outside resulting very low even negative electron affinity. Superhalogen on the otherhand mimic the chemistry of halogen having electron affini...
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... regain the 6p electrons required by Huckel's rule of aromaticity, all of the systems required one extra electron. To determine whether this extra electron makes any difference in the electron affinity (EA) values, we optimized both the anionic and neutral forms of the B-substituted heterocycles. All of the optimized structures are shown in (ESI, Fig. 2 †). The schematic representations of such systems are given in Fig. 2 and their EA values are tabulated in Table 2. From the table it is evident that all of the EA values became positive aer boron substitution in the ring but not enough to have superhalogen properties. To have superhalogen properties, molecules should display EA values ...
Context 2
... of the systems required one extra electron. To determine whether this extra electron makes any difference in the electron affinity (EA) values, we optimized both the anionic and neutral forms of the B-substituted heterocycles. All of the optimized structures are shown in (ESI, Fig. 2 †). The schematic representations of such systems are given in Fig. 2 and their EA values are tabulated in Table 2. From the table it is evident that all of the EA values became positive aer boron substitution in the ring but not enough to have superhalogen properties. To have superhalogen properties, molecules should display EA values higher than that of chlorine (3.6 eV). As an example, the EA values ...
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... When two semiconductor materials with different work functions, band gaps, and electron affinities combine to form a device, alignment of the Fermi level causes discontinuities within the bands [39]. According to Anderson's principle [52], the discontinuities in the conduction band (ΔE c ) are equal to the difference in the electron affinities χ of the two semiconductor materials under the ideal condition of free interface states and vacuum level alignment: ...
... The excitons are split into electrons and holes at the Ir(ppy) 3 /Si contact. In an electric field, electrons are carried quickly into the silicon and gathered by the aluminum electrode, whereas holes are moved into the Ir(ppy) 3 to the gold electrode [52]. We obtained the Table 4. ...
... We obtained the Table 4. The values of both the filling factor FF and the photoefficiency η can be estimated using [52]: (14) η = FFV OC I SC /AP In (15) where P In = 50 mW/cm 2 is the intensity of the halogen lamp. We found the values of these quantities to be FF = 0.33 and η = 5.33%. ...
... The designed additives C 2 HBNO(NO 2 ) 2 and C 2 HBNS(NO 2 ) 2 were derived from the five-membered organic heterocyclic molecules; isoxazole (C 3 H 3 NO) and thiazole (C 3 H 3 NS) [31,33]. At first, one ring carbon atom was replaced by boron in isoxazole and thiazole. ...
... Apart from these two molecules, to mimic the structural pattern of TPFPB (B(C 6 H 5 ) 3 ), the boron-based trimer of these compounds having chemical formula B[C 2 HBNO(NO 2 ) 2 ] 3 , and B [C 2 HBNS(NO 2 ) 2 ] 3 were also designed. The details of the study can be found somewhere else [31,33]. ...
Development of new solvent/additive electrolyte is emerging field of research towards the improvement of ion transport and solid-electrolyte-interface formation in Li-ion battery (LIB). We perform extensive atomistic molecular dynamics simulations with LiPF6 in ethylene carbonate (EC) in presence of a new class of boron (B) based heterocyclic anion receptor additives; C2HBNO(NO2)2, and C2HBNS(NO2)2 and their trimers B[C2HBNO(NO2)2]3, and B[C2HBNS(NO2)2]3 to investigate the efficacy of this class of additives in regulating the solvation and transport properties of Li⁺ ions as compared to the reference LiPF6/EC solution that contained TPFPB, a commonly used B-based additive. Our designed additives in several aspects show their efficacy. Among all, C2HBNS(NO2)2 is found to be the most efficient PF6⁻ trapper that reduces ion pair formation. It promotes diffusion of Li⁺ and EC, improves the transference number, and reduces viscosity of solution, as compared to TPFPB. Further, it improves the ionic conductivity and drift velocity under a wide range of temperatures and external electric fields, respectively. Some of the computed properties are in agreement with the available experimental results. Our study would facilitate the design and synthesis of this class of additives to open up new possibilities of accelerating the LIB power sources for portable appliances.
... This suggests that 'A' should have a high electron affinity. Pursuing this logic, several findings have been published using the tool of superhalogens, [21][22][23][24][25][26][27][28][29][30][31][32][33] which are characteristic of having extremely high electron affinities. While the concept of superhalogens was first introduced in the 80's by Gutsev and Boldyrev,22,23 the first experimental proof came in 1999 from Wang et al. 34 By using the photoelectron spectroscopy technique, they have shown the existence of superhalogen anions such as MX 2 À (M = Li, Na; X = Cl, Br, I) and MX 3 À (M = Be, Mg, Ca; X = Cl, Br). ...
The unexplored area of organic superacids was investigated in terms of both Brønsted and Lewis concepts of acids and bases. The primary requirement of a superacid-high affinity for electron/fluoride ions was fulfilled using two strategies: (i) using the superhalogen-type heterocyclic framework and (ii) selecting systems that have an electron count one short of attaining (4n + 2) Hückel aromaticity. With these in mind, eleven systems were considered throughout the study, expected to cross the target of 100% H2SO4 acidity and/or the fluoride affinity of SbF5. To enhance the pKa and F− affinity values of the considered systems, electron-withdrawing ligands F and CN were employed. The superhalogen and aromaticity properties were verified by vertical detachment energy (VDE) and nucleus independent chemical shift (NICS) calculations, respectively. Finally, the collective effect of the potential super Lewis acids was looked into using a BL3 skeleton with them acting as ligands.
... We also wish to point out that boron was replaced with carbon in the bodipy group for docking of BD-CsA. Although the substitution of boron with carbon has been used by others (Bonacorso et al., 2018;Naaresh Reddy and Giri, 2016;Verwilst et al., 2017;Zhao et al., 2017) and us (Fig. 10), the interaction of boron compared to carbon in the BD-CsA with residues in the drug-binding pocket of P-gp might be somewhat different. Resolution of the atomic structure of P-gp bound to BD-CsA would help to resolve this issue. ...
Fluorescent conjugates of drugs can be used to study cellular functions and pharmacology. These compounds interact with proteins as substrates or inhibitors, helping in the development of unique fluorescence-based methods to study in vivo localization and molecular mechanisms. P-glycoprotein (P-gp, ABCB1) is an ATP-binding cassette (ABC) transporter that effluxes most anticancer drugs from cells, contributing to the development of drug resistance. To study the transport function of P-gp, we synthesized a Bodipy-labeled fluorescent conjugate of cyclosporine A (BD-CsA). After synthesis and characterization of its chemical purity, BD-CsA was compared with the commonly used 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-CsA probe. In flow cytometry assays, the fluorescence intensity of BD-CsA was almost 10 times greater than that of NBD-CsA, enabling us to use significantly lower concentrations of BD-CsA to achieve the same fluorescence levels. We found that BD-CsA is recognized as a transport substrate by both human and mouse P-gp. The rate of efflux of BD-CsA by human P-gp is comparable to that of NBD-CsA. The transport of BD-CsA was inhibited by tariquidar, with similar IC50 values to those for NBD-CsA. BD-CsA and NBD-CsA both partially inhibited the ATPase activity of P-gp with similar IC50 values. In silico docking of BD-CsA and NBD-CsA to the human P-gp structure indicates that they both bind in the drug-binding pocket with similar docking scores and possibly interact with similar residues. Thus, we demonstrate that BD-CsA is a sensitive fluorescent substrate of P-gp that can be used to efficiently study the transporter's localization and function in vitro and in vivo. SIGNIFICANCE STATEMENT: The goal of this study was to develop an effective probe to study drug transport by P-glycoprotein (P-gp). Fluorophore-conjugated substrates are useful to study the P-gp transport mechanism, structural characteristics, and development of its inhibitors. Cyclosporine A (CsA), a cyclic peptide comprising 11 amino acids, is a known substrate of P-gp. P-gp affects CsA pharmacokinetics and interactions with other coadministered drugs, especially during transplant surgeries and treatment of autoimmune disorders, when CsA is given as an immunosuppressive agent. We synthesized and characterized Bodipy-FL-CsA as an avid fluorescent substrate that can be used to study the function of P-gp both in vitro and in vivo. We demonstrate that Bodipy-FL-conjugation does not affect the properties of CsA as a P-gp substrate.
... We also replaced boron with carbon in the bodipy group for docking of BD-CsA. Although the substitution of boron with carbon has been used by others (Naaresh Reddy and Giri, 2016;Verwilst et al., 2017;Zhao et al., 2017;Bonacorso et al., 2018) and by us (Fig. 10), the interaction of boron compared with carbon in the BD-CsA with residues in the drug-binding pocket of P-gp might be different. Resolution of the atomic structure of P-gp bound to BD-CsA would help to resolve this issue. ...
Generation of fluorescent conjugates of small molecules and existing drugs has facilitated their use in addressing cellular functions and pharmacological analysis. These compounds interact with several proteins as substrates or inhibitors, thus allowing the development of unique fluorescence‐based methods to study in vivo localization and the molecular mechanisms. Pglycoprotein (P‐gp) is an ATP‐binding cassette transporter that effluxes most anti‐cancer drugs from cells, contributing to the development of drug resistance in cancer cells. P‐gp, which exports toxic metabolites and xenobiotics, is expressed on the surface of epithelial cells of the intestine, kidney, liver, placenta, adrenal gland and endothelial cells at blood‐brain barrier. With the aim of developing an effective probe to study drug‐transport by P‐gp in various model systems including cultured cells, mice and zebra fish, we synthesized a BODIPY‐FL conjugate of cyclosporine A (BD‐CsA). After synthesis and characterization of its chemical purity, BD‐CsA was compared with the currently available 7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl (NBD)‐CsA probe in terms of its usage as a substrate of human and mouse P‐gp. Using a BacMam baculovirus HeLa cell expression system and a flow cytometry‐based transport assay, we found that BD‐CsA is recognized as a substrate by both human and mouse P‐gp. The rate of efflux of BD‐CsA by human P‐gp is similar to that of NBD‐CsA (T 1/2 of 5.0 min and 3.0 min for BD‐CsA and NBD‐CsA, respectively). In flow cytometry assays, the fluorescence intensity of BD‐CsA was almost 10‐times higher than that of NBD‐CsA due to the high fluorescence quantum yield of the BODIPY fluorophore, allowing us to use significantly lower concentrations of BD‐CsA to achieve the same fluorescence levels. The transport of BD‐CsA was inhibited by the P‐gp inhibitor tariquidar, with similar IC 50 values as for NBD‐CsA transport (21.6 nM for BD‐CsA and 25.8 nM for NBD‐CsA). We also observed that both BD‐CsA and NBD‐CsA partially inhibited the ATPase activity of P‐gp. In silico docking of BD‐CsA and NBD‐CsA to the homology model of human P‐gp indicates that both probes bind in the drug‐binding pocket of Pgp with similar docking scores. Thus, we demonstrate that BD‐CsA is a sensitive and efficient fluorescent substrate of P‐gp that can be used to study the transporter's function in both in vitro and in vivo settings.
Support or Funding Information
This research was funded by the Intramural Research Program of the National Institutes of Health, the National Cancer Institute, Center for Cancer Research
This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
... Out of the five, two are six membered and three are five membered heterocycles. It has been reported that these unsubstituted heterocycles are not superhalogens (SH) but, when the H's are substituted by F and CN, most of the complexes become superhalogens 35 having the vertical detachment energies (VDEs) ranging between approximately 3.0 eV and 5.87 eV. Since we are interested in designing halogen free electrolytes, we have substituted H by NO 2 , which has a strong electron withdrawing nature than that of F and CN to get our desired superhalogens. ...
Inorganic superhalogens are commonly used as anionic counterparts in Li-ion batteries. In an endeavour to prepare better electrolytes, we have modelled the anionic part with different organic heterocyclic-based superhalogens. First principle calculations on those organic superhalogens reveal that the Li-binding energy is at par with that of the Li-salt of a common electrolyte. Out of five different halogen free organic heterocycles, Li[C3BN2(NO2)4] and Li[C2BNO(NO2)3] are found to be most suitable as electrolytes in Li-ion batteries. Molecular dynamics simulation studies on C2BNO(NO2)3-, C3BN2(NO2)4-, Li[C3BN2(NO2)4], and Li[C2BNO(NO2)3] also reveal that the structures are dynamically stable.
The role of boron-doped thiazoles as a Lewis acid catalyst in [4+2] cycloaddition reaction between 1,3-butadiene and acrolein has been addressed. Three different organic heterocycles were designed to study their catalytic activity. It has been observed that these heterocycles efficiently work as catalysts than the well-known Lewis acid BF3. All the reactions follow the normal electron demand process and are exothermic. Different conceptual DFT-based reactivity descriptors and electronic structure principles such as maximum hardness and minimum electrophilicity lend additional support to the feasibility of the reaction mechanism. The reaction force (RF), reaction electronic flux (REF), and its different components exhibit a detailed electronic activity throughout the reaction.
The ab-initio calculation shows that nitrogen, boron, and sulfur (NBS) containing heterocyclic molecules, i.e., boron-doped thiazole, can behave as a superhalogen with high electron affinity value. In this study, DFT calculation found that the calculated electron affinity/vertical detachment energy of the synthesized dimer-NBS heterocyclic molecules is close to 2 eV. After ligand manipulation on the dimer, new superhalogens developed. Frontier molecular orbitals (FMOs) study helps to understand the variation of the electron affinity of the designed superhalogens. Topological analyses such as bond critical point (BCP), electron localization function (ELF), and AdNDP analysis support the bonding pattern of such heterocycle molecules.
Polycyclic hydrocarbon (PH) radicals and anions such as C9H7-, C11H7-, C13H9-, and C15H9- generally possess low electron affinity (EA) and vertical detachment energy (VDE), respectively, due to their aromaticity and, consequently, enhanced stability. In this work, we propose a simple strategy to design polycyclic superhalogens (PSs) by replacing all hydrogens by cyano (CN) groups. Superhalogens can be defined as the radicals having higher EA than halogens or anions having higher VDE than halides (3.64 eV). Our density functional calculations suggest that the EA (VDE) of PS radicals (anions) exceeds 5 eV. All these PS anions are aromatic, except C11(CN)7-, which is anti-aromatic. The superhalogen property of these PSs can be attributed to the EA of CN ligands, leading to the delocalization of extra electronic charge significantly as explained using prototype C5H5-x(CN)x systems. We also notice that the 'superhalogenity' (superhalogen behavior) of C5H5-x(CN)x- is directly related to their aromaticity. We have also shown that the substitution of CN is energetically favorable, which confirms their experimental viability. Our findings should motivate experimentalists to synthesize these superhalogens for further exploration and future applications.
