Dinitrile Compound Research Articles

Photoinduced [3+2] Cycloaddition of Carbenes and Nitriles: A Versatile Approach to Oxazole Synthesis.

We have developed a photoinduced protocol for the synthesis of pharmaceutically important oxazole molecules using diazo- and nitrile-containing reactants. The process involves the initial photolysis of the diazo compound to afford singlet carbenes, which are tapped by nitriles in a [3+2] cycloaddition fashion to give substituted oxazoles. With di-nitrile compounds, useful bis-oxazoles were obtained. The applicability of the transformation is showcased through the expedient synthesis of small-molecule drugs and biologically relevant molecules such as felbinac, pimprinine, texamine, ugnenenazole etc. The protocol is also useful for the generation of 2 H and 13 C isotope labelled oxazoles. Merging photolysis with continuous-flow chemistry was demonstrated for scaling up the reaction. The non-requirement of metal catalysis or photosensitizers to harness the light energy with blue light sufficing the execution of the reaction makes it a versatile and general protocol for the synthesis of structurally diverse oxazoles.

Ratiometric fluorescent strategy for malononitrile determination in organic and aqueous medium and biological imaging

Malononitrile is a versatile dinitrile compound with high reactivity, which has wide prospect in application for multisynthetic organic medical chemistry and industrial manufacture. Considering of the transformation to HCN in animal tissue metabolism, malononitrile has potential environmental pollution and health risks. Here, a ratiometric fluorescent probe 4-(benzothiazol-2-yl)-2-hydroxy benzaldehyde (HBTA) for detection of malononitrile in organic and aqueous phase is developed on the basis of reaction-triggered fluorophore for the first time. The ratiometric assay with malononitrile-responsive fluorescence signal was contributed by Knoevenagel condensation and intramolecular cyclization, which was confirmed by HR-MS analysis and NMR titration spectra. In addition, this ratiometric probe provided a fancy strategy for detection of malononitrile with fast response, high sensitivity and selectivity, declaring excellent imaging performance in vivo capable of semi-quantification for malononitrile level.

Synthesis of fluorine-containing phthalocyanines and investigation of the photophysical and photochemical properties of the metal-free and zinc phthalocyanines

Abstract 4-(3-(Trifluoromethyl)benzylthio)phthalonitrile (1) was synthesized. Metal-free phthalocyanine 2, zinc(II) phthalocyanine 3 and cobalt(II) phthalocyanine 4 were synthesized starting with dinitrile compound 1. Photodynamic therapy properties of 2 and 3 were studied.

Multifaceted adsorption of α-cyano-4-hydroxycinnamic acid on silver colloidal and island surfaces

The surface adsorption of organic nitrile compounds on the silver colloidal and island surfaces has been studied using surface-enhanced Raman scattering (SERS). α-Cyano-4-hydroxycinnamic acid (CHCA) with nitrile and carboxyl groups shows various surface adsorption on the silver surfaces. In acidic conditions, the surface adsorption of CHCA via the nitrile group with a more or less tilted geometry to the surface was found. When the solution pH increases, the carboxylate and nitrile groups of deprotonated CHCA participate in the surface adsorption, whereas the molecular plane of CHCA becomes more parallel to the surface. The ν(CN) band in SERS of CHCA is the indicator of the surface adsorption geometry. The strongly red-shifted and broadened ν(CN) band in SERS represents the surface adsorption via π-electrons of the CN bond (side-on geometry; π-coordination). Nitriles adsorbed on the surface via the nonbonding electron pair of the nitrogen atom (end-on geometry; σ-coordination) often cause the blue-shifts and small band broadening in ν(CN) in SERS. The surface adsorption geometry of organic nitriles based on many previous experimental results was further confirmed by the surface adsorption of CHCA on the silver island surfaces and dinitrile compounds on the silver colloidal surfaces.

Development of Multiactive Site Catalysts for Surface Concerted Catalysis Aimed at One-Pot Synthesis

Abstract Multiactive site catalysts have been developed for conducting one-pot synthesis and highly efficient reactions based on the principle of concerted catalysis. Ru-grafted hydrotalcite containing both Ru and base sites on its outer surface exhibits high catalytic activity for the one-pot synthesis of dinitrile compounds. A reaction system consisting of a strong acid, base, and Pd species is capable of catalyzing a one-pot process consisting of five successive reactions, esterification, deacetalization, aldol reaction, hydrogenation, and Michael reaction, to produce a final product, 2,4-dicyanoester, from starting materials containing cycnoacetic acid and acetal, with excellent overall yield. Immobilization of an amine base onto a solid acid surface affords an acid–base bifunctional catalytic surface with controlled acid–base interactions. Various nucleophilic addition reactions including the one-pot synthesis of dinitroalkane derivatives proceeds effectively by acid–base concerted catalysis. The concept of concerted catalysis on solid surfaces can be extended to synergistic/double-activation catalysis between a metal complex and organic base immobilized on a surface. Further, the concept of multiactive site catalysis can also be applied to a homogeneous catalyst system. For example, a Cu-bisphosphine complex exhibits excellent catalytic performance for the transformation of CO2 to valuable chemicals, such as cyclic carbonate, silyl formate, and formamides.

Practical Sulfolane-Based Electrolytes: Choice of Li Salt for Graphite Anode Operation

In the last years, continuous attempts have been made to increase further the energy density of Li-ion batteries and cathode materials operating above 4.5V versus Li+/Li have been proposed since the late 90’s, such as LiNi0.5Mn1.5O4 [1], or LiCoPO4F [2]. However, the so-called ‘5V’ Li-ion battery is still not on a reality, due to the lack of adapted electrolyte. Several reports deal with high voltage electrolytes such as ionic liquids, alkyl dinitrile compounds or fluorinated alkylcarbonates. Besides, alkyl sulfone-based electrolytes [3] are also promising and among them, Sulfolane (tetramethylene sulfone, SL), as a by-product of the oil industry and thus cheap and produced by tons, is an attracting candidate for practical electrolytes. SL, regardless of its high viscosity, is known for leading to Li-ion electrolytes with high anodic stability. This is not only supported by experimental results [4] [5] but can also be explained by fundamental studies using Quantum Chemistry [6] and Molecular Dynamics [7]. Mixtures of sulfolane and low dielectric co-solvent seem able to allow room temperature operation of high voltage electrodes but to the best of our knowledge, no report can be found on a sulfolane-based electrolyte allowing efficient graphite cycling, which is a prerequisite for high energy density batteries. In fact, the SEI formed on graphite and its effect on battery performance is at least as influential as the electrolyte intrinsic properties such as its conductivity, given its role in capacity loss and rate performance. Thus, we report not only on the intrinsic physico-chemical properties of SL/DMC mixtures including a variety of Li salts, both inorganic and organic (LiBF4, LiPF6, LiDFOB, LiBOB, LiTFSI, LiFSI, LiTDI), but also on the effect of the salts on the cycling behavior of graphite electrodes in these ‘high voltage’ electrolytes. As shown in Figure 1, some of the electrolytes are as conductive as state-of-the-art alkyl carbonate-based electrolytes with values above 7 mS cm-1 at 20°C and most are still well conductive at -20°C. Figure 2 shows an example of cycling results of 5.5 mg cm-2 graphite electrodes obtained with 1M LiFSI and LiDFOB-based electrolytes in half-cells without additive. As can be seen, both salts allow efficient cycling with first cycle efficiencies above 90% and LiFSI allows for the steadiest cycling. Acknowledgements The research presented is part of the ‘SPICY’ project funded by the European Union’s Horizon 2020 research and innovation program under grant agreement N° 653373.

Development of Sulfolane-Based Electrolytes for Li-ion batteries

The quest for higher energy density Li-ion batteries pushes toward ‘high voltage’ cathode operating above 4.5V. However, if such materials have been proposed for many years in the case of LiNi0.5 Mn1.5 O4 1 or more recently for LiCoPO4F2, the implementation of such materials is currently prevented by the lack of adapted electrolyte. Several reports deal with high voltage electrolytes such as ionic liquids, dinitrile compounds or fluorinated carbonates. Yet, another class of solvents investigated are the alkyl sulfone, linear3 or cyclic4. Among them, sulfolane, despites its high viscosity has been reported to allow low potential anode operation (such as Li metal or graphite), while other reports point out the high oxidative stability of the electrolytes made thereof4, which was explained based on fundamental studies such as QC5 and MD6. Mixtures of sulfolane seem able to allow room temperature operation of both graphite and high voltage electrodes but no report can be found of a sulfolane-based electrolyte compatible, at the same time, with graphite and a high voltage electrodes. Thus, we examine here the possibility of forming new electrolyte system, based on sulfolane/DMC mixtures for room temperature operation. In particular, the role of the Li salt has been investigated as it is known to play a role on conductivity, via viscosity and dissociation in a solvent system that has a lower dielectric constant and higher viscosity than alkyl carbonate mixtures such as EC/DMC. In addition, keeping the application in mind, SEI building on graphite and aluminum current collector corrosion are also dependent on the Li salt or mixture used. Thus several inorganic and organic Li salts have been investigated in terms of conductivity and electrochemical stability and tested versus graphite and LiNi0.5 Mn1.5 O4 electrodes in a DMC/sulfolane mixed solvent.

Synthesis and Characterization of New Phthalocyaninato Cobalt Complexes Containing Crown Ether Linked 1,8-Disubstituted Anthraquinones

The synthesis of novel cobalt(II) phthalocyanine complexes, peripheral symmetrically derived from 5,28-dioxo-5,11,12,14,15,22,23,25,26,27-decahydro-10H-4,6-methanotribenzo [e,n,q][1,4,7,10,13,19] tetraoxadiazacyclohenicosine-18,19-dicarbodinitrile or 5,28-dioxo-11,12,14,15,22,23,25,26-octahydro-5H-4,6-methanotribenzo [h,q,f] [1,4,7,10,13,16]hexa-oxacyclohenicosine-18,19-dicarbodinitrile were performed. These compounds were prepared starting 4,5-dihydroxy-1,2-phthalonitrile and 1,8-bis{[2-[2-{[(4-methylphenyl) sulfonyl]oxy}ethoxy]ethyl]amino}-9,10-anthracenedione or 1,8-bis[2-(2-iodoethoxy)ethoxy]-9,10-anthracenedione. Cobalt phthalocyanine complexes were prepared from dinitrile compounds and anyhydro cobalt(II)chloride. The novel compounds were characterized by a elemental analysis, FT-IR, UV-vis, 1H NMR, 13C NMR, and MS.

Dinitrile compound containing ethylene oxide moiety with enhanced solubility of lithium salts as electrolyte solvent for high-voltage lithium-ion batteries

A dinitrile compound containing ethylene oxide moiety (4,7-dioxa-1,10-decanedinitrile, NEON) is synthesized as an electrolyte solvent for high-voltage lithium-ion batteries. The introduction of ethylene oxide moiety into the conventional aprotic aliphatic dinitrile compounds improves the solubility of lithium hexafluorophosphate (LiPF6) used commercially in the lithium-ion battery industry. The electrochemical performances of the NEON-based electrolyte (0.8 M LiPF6 + 0.2 M lithium oxalyldifluoroborate in NEON:EC:DEC, v:v:v = 1:1:1) are evaluated in graphite/Li, LiCoO2/Li, and LiCoO2/graphite cells. Half-cell tests show that the electrolyte exhibits significantly improved compatibility with graphite by the addition of vinylene carbonate and lithium oxalyldifluoroborate and excellent cycling stability with a capacity retention of 97 % after 50 cycles at a cutoff voltage of 4.4 V in LiCoO2/Li cell. A comparative experiment in LiCoO2/graphite full cells shows that the electrolyte (NEON:EC:DEC, v:v:v = 1:1:1) exhibits improved cycling stability at 4.4 V compared with the electrolyte without NEON (EC:DEC, v:v = 1:1), demonstrating that NEON has a great potential as an electrolyte solvent for the high-voltage application in lithium-ion batteries.

Synthesis of metal-free and zinc phthalocyanines containing 2-pyridyl-methyl pendant arm linked with NS4-donor macrocyclic moiety and their selectivity towards Cu(II) cations

New phthalonitrile (L1), metal-free phthalocyanine (H2Pc) and zinc-phthalocyanine (ZnPc) substituted in peripheral positions with 2-pyridyl methyl pendant arm linked mixed donor macrocyclic ligands have been prepared in a multi-step reaction sequence. The novel compounds were characterized by a combination of elemental anlaysis, 1 H NMR, 13 C NMR, IR, UV-vis and MS spectral data. The influence of metal cations such as Cd 2+, Zn 2+, Hg 2+, Al 3+, Fe 3+ and Cu 2+ on the spectroscopic properties of dinitrile compound L1 and free phthalocyanine H2Pc was investigated by means of absorption spectrophotometry. Spectrophotometric titrations were carried out with these ligands for Cu 2+ ion. The complex composition of Cu - L1 was found 1:1 by means of spectrophotometric titration data. The spectrophotometric method showed good sensitivity for Cu 2+ with linear range of 2.6 × 10-6 to 1.3 × 10-4 M with dinitrile compound.

Synthesis, characterization, spectral and electrical properties of peripherally tetratriazole-substituted phthalocyanines and its metal complexes

The substituted [1,2,4]triazole 3 was obtained from the reaction between compound 1 and compound 2. Novel substituted phthalonitrile 5 was prepared by the substitution of the nitro group of 4-nitrophthalonitrile 4 with triazole moiety 3. The synthesis of metal-free, zinc, nickel, cobalt and copper phthalocyanines with four substituted [1,2,4]triazole groups on peripheral position were performed from cyclotetramerization of novel substituted dinitrile compound 5. Metal-free phthalocyanine 6 and its Zn-, Ni-, Co- and Cu- complexes 7–10 were prepared in DMAE at reflux temperature. All new compounds were characterized by a combination of elemental analyses, IR, 1H/13C NMR, MS and UV–vis spectroscopy. Aggregation behaviors of NiPc 8 and CuPc 10 were also investigated. While NiPc 8 was aggregated in acetone, DMF, DMSO, THF, ethylacetate and toluene and non-aggregated in dichloromethane and pyridine at 10 × 10−6 mol dm−3 concentration, CuPc 10 showed monomeric behavior in dichloromethane, DMSO, DMF, pyridine, THF and showed aggregation in acetone, ethylacetate and toluene at 14 × 10−6 mol dm−3 concentration. On the other hand, substituted NiPc 8 and CuPc 10 did not show aggregation behavior between 4 × 10−6–14 × 10−6 mol dm−3 concentration range in chloroform. Dc and ac conductivity and Impedance Spectroscopy (IS) studies were also done on thin films of compounds 6, 7, 8, 9 and 10 as a function of temperature (295–523 K) and frequency (40–105 Hz) under vacuum (∼2 × 10−3 mbar) in dark. The compounds 7, 8, 9 and 10 showed nearly same dc conductivity values in the measured temperature range. Variation of dc conductivity of 6, 7, 8, 9 and 10 with temperature exhibited the semiconducting behavior. Variation of ac conductivity of the films with frequency represented by the function σac = Aωs. The results indicated that charge transport mechanism of the films can be explained by hopping and small polaron tunneling model for 6, 7, 8, 9 and 10 depending on temperature and frequency region. Results of the impedance spectra measurements showed that, at high temperatures, depressed semicircles with different radius indicate deviation from Debye dispersion relation.

New type of tetrazine‐substituted metallophthalocyanines by microwave irradiation: Synthesis and characterization

Abstract5,6‐bis(4‐methylphenyl)‐2,3‐dihydro‐1,2,3,4‐tetrazine 2 was synthesized by the dimerization of ethyl p‐methylbenzoateformylhydrazone 1 in hydrazinehydrate solution. 2,3‐bis(4‐methylphenyl)‐6,7,14,15‐tetrahydro[1,2,3,4]tetrazino [2,3d][1,8, 4,5]benzodithia‐diazecine‐10,11‐dicarbonitrile 4 was sythesized by cyclization reaction of tetrazine monomer 2 onto 1,2‐bis‐(2‐iodoethylmercapto)‐4,5‐dicyanobenzene 3. Co(II) and Cu(II) phthalocyanine complexes were prepared by reaction of the dinitrile compound (4) with the chlorides of Co(II), Cu(II), and DMAE at 175°C, 350 W in a microwave oven for 10 min. Zn(II)‐phthalocyanine complex was prepared by reaction of the dinitrile compound 4 with the acetate of Zn(II) and DMAE at 175°C, 350 W in a microwave oven for 10 min. The new compounds were characterized by a combination of IR, 1H‐NMR, 13CNMR, UV‐vis, elemental analysis, and MS spectral data. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:456–461, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20623

Synthesis, characterization and electrochemistry of a new organosoluble metal-free and metallophthalocyanines

4-[2-(Phenylthio)ethoxy]phthalonitrile 3 was synthesized by nucleophilic displacement of nitro group in 4-nitrophthalonitrile with 2-(phenylthio)ethanol 1. The metal-free phthalocyanine 4 was prepared by the reaction of a dinitrile monomer with 2-(dimethylamino)ethanol. Ni(II), Co(II), Cu(I) phthalocyanines 5, 7, 8 were prepared by reaction of the dinitrile compound with the chlorides of Ni(II), Co(II), Cu(I) in DMAE. Zn(II) phthalocyanine 6, was prepared by reaction of the dinitrile compound with the acetates of Zn(II) in DMAE. Electrochemical behaviours of novel metal-free, Co(II) and Zn(II) phthalocyanines were investigated by cyclic voltammetry, potential differential pulse voltammetry techniques. The new compounds were characterized by a combination of IR, 1H NMR, 13C NMR, UV–Vis, elemental analysis and MS spectral data.

Highly Blue Luminescent Triazine−Amine Conjugated Oligomers

[Reaction: see text]. The novel synthetic strategy and optical properties of highly fluorescent, triazine-amine conjugated oligomers are described herein. Under basic conditions, aromatic dinitrile compounds, NC-C6H4-X-C6H4-CN (X = NMe, O, CH2), underwent cyclic trimerization of the cyano groups at both ends to give a series of triazine-containing oligomers. The oligomers can be expressed as (2n + 1) mer, where n represents the number of triazine rings in the oligomer. The absorption maximum of an amine-conjugated trimer (X = NMe, n = 1) was outstandingly red-shifted as compared with those of the other trimers (X = CH2, O). In acidic media, the amine-conjugated trimer showed two-step bathochromic shifts caused by protonation. The absorption maxima of the amine-conjugated (2n + 1) mers (X = NMe, n = 1-4) did not depend on n; instead, shoulder peaks appeared in the long-wavelength region when n 2. The oligomers involving alternate conjugation of triazines and NMe groups through phenylene groups showed strong fluorescence in chloroform. In particular, the pentamer was the most efficient blue emitter (PhiF = 0.82). The other triazine-containing oligomers (X = CH2, O) did not show fluorescence at all. Therefore, it is concluded that the emission properties are due to the strong electron-donating and accepting abilities of the NMe and triazine moieties, respectively.

An Investigation of the Mesogenic Properties of Dibenzoquinoxaline Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.

An investigation of the mesogenic properties of dibenzoquinoxaline derivatives

The syntheses of two new discotic molecules based on the dibenzoquinoxaline core are reported; comparison of their phase behaviors to a known dinitrile compound demonstrates the importance of specific functional groups in stabilizing columnar mesophases.

Synthesis and properties of new soluble triphenylamine-based aromatic poly(amine amide)s derived fromN,N?-bis(4-carboxyphenyl)-N,N?-diphenyl-1,4-phenylenediamine

A new triphenylamine-containing aromatic dicarboxylic acid, N,N-bis(4- carboxyphenyl)-N,N-diphenyl-1,4-phenylenediamine, was synthesized by the conden- sation of N,N-diphenyl-1,4-phenylenediamine with 4-fluorobenzonitrile, followed by the alkaline hydrolysis of the intermediate dinitrile compound. A series of novel triphenylamine-based aromatic poly(amine amide)s with inherent viscosities of 0.50 - 1.02 dL/g were prepared from the diacid and various aromatic diamines by direct phosphorylation polycondensation. All the poly(amine amide)s were amorphous in nature, as evidenced by X-ray diffractograms. Most of the poly(amine amide)s were quite soluble in a variety of organic solvents and could be solution-cast into transpar- ent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with glass-transition temperatures up to 280 °C, 10% weight-loss temperatures in excess of 575 °C, and char yields at 800 °C in nitrogen higher than 60%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 94 -105,

Regioselective biotransformation of the dinitrile compounds 2-, 3- and 4-(cyanomethyl) benzonitrile by the soil bacterium Rhodococcus rhodochrous LL100–21

The cyanomethyl benzonitrile compounds used for this study contain two cyano groups: a −CH2CN side chain, plus a cyano group attached to the benzene ring. The ortho, meta and para −CH2CN substituted compounds were biotransformed using whole cell suspensions of the bacterium Rhodococcus rhodochrous LL100–21. The bacterium had previously been grown on the mono-nitrile compounds propionitrile, benzonitrile or acetonitrile, inducing the formation of nitrile hydrolyzing enzymes.Suspensions of R. rhodochrous LL100–21 that had been grown on propionitrile or benzonitrile converted the aliphatic group of 2-(cyanomethyl) benzonitrile (a) to the corresponding carboxylic acid, 2-(cyanophenyl) acetic acid (d) with excellent recovery of the product and no evidence for any other products. Conversely, when grown on acetonitrile the bacterium converted 2-(cyanomethyl) benzonitrile (a) to the amide derivatives 2-(cyanophenyl) acetamide (k) and 2-(cyanomethyl) benzamide (l) but only in low yields.Biotransformations of 3-(cyanomethyl) benzonitrile (b) and 4-(cyanomethyl) benzonitrile (c), by suspensions of bacteria that had been grown on benzonitrile or propionitrile, resulted in hydrolysis of the aromatic nitrile to produce 3- and 4-(cyanomethyl) benzoic acid (j) and (m), respectively, both with a high yield. Low concentrations of other products were also detected, for example the diacids 3- and 4-(carboxyphenyl) acetic acid (h) and (i).When the bacterium was grown on acetonitrile it could biotransform 3- and 4-(cyanomethyl) benzonitrile (b) and (c) to different products indicating less regiospecificity by the nitrile hydratase enzyme.Comparison of the initial rates of conversion of the aliphatic cyano side chain of 2-(cyanomethyl) benzonitrile (a) and other substituted benzonitriles indicated that electronic effects did not affect the initial rate of the reaction as they would require transmission through an SP3 methylene carbon atom.

A Pseudomonas putida capable of stereoselective hydrolysis of nitriles

Pseudomonas putida NRRL-18668 contains a nitrile hydratase capable of stereoselective hydrolysis of 2-(4-chlorophenyl)-3-methylbutyronitrile at more than 90 % enantiomeric excess (ee) to the (S)-amide. This soil isolate was recovered from enrichments using (R,S)-2-methylglutaronitrile as the sole nitrogen source. Enzyme expression is constitutive and does not show a high level of catabolite repression. The organism is capable of growth on a wide variety of aliphatic mono- and dinitrile compounds. The hydrolysis activity on propionitrile is approximately 10.3 μmole h−1 mg wet cells−1. The enzyme in cell-free preparations is inhibited by a number of heavy metals, phenylhydrazine, and cyanide. Substrate specificity is broad with highest rates shown on C4 and C5 aliphatic mononitriles. The strain appears somewhat unusual in its dependence on cobalt supplementation for maximum enzyme activity and the ability to hydrolyze some aromatic nitriles. This strain is also capable of a two-step hydrolysis of 2-(4-isobutylphenyl)-propionitrile and 2-(6-methoxy-2-napthyl)-propionitrile to the (S)-acids (ibuprofen and naproxen respectively) with stereoselectivity residing primarily in the aliphatic amidase. This appears to be the first description of a steroselective nitrile hydratase from a gram-negative organism.

Blocking actions of BIDN, a bicyclic dinitrile convulsant compound, on wild-type and dieldrin-resistant GABA receptor homo-oligomers of Drosophila melanogaster expressed in Xenopus oocytes

The receptor antagonist actions are described for a novel bicyclic dinitrile compound (BIDN, 3,3-bis-(trifluoromethyl)-bicyclo [2.2.1] heptane-2,2-dicarbonitrile) on a Drosophila melanogaster homo-oligomeric GABA receptor expressed in Xenopus oocytes. BIDN blocked the wild-type form of the receptor in a neither purely competitive, nor purely non-competitive manner, being dependent on the GABA concentration yet insurmountable, and block was independent of the membrane potential. BIDN was found to be less effective against a mutant (A 302 → S) form of the receptor resistant to dieldrin and picrotoxinin. This cross resistance of dieldrin-resistant receptors to BIDN is of interest in the light of recent findings that BIDN binding to insect membranes is displaced competitively by dieldrin, but not by picrotoxinin.