Ternary Molecular Complex Research Articles

All good things come in threes: first example of a trimorphic, ternary molecular salt complex

A ternary complex made up of trinitrobenzene, 2-aminopyridinium and 9-anthracenecarboxylate crystallizes out in three polymorphic forms, giving yellow, orange and red coloured crystals.

Ligand Fingerprinting in the Membrane Dynamics of Single TrkA and P75NTR Neurotrophin Receptors

We have sought to investigate the responses of Nerve Growth Factor (NGF) receptors TrkA and P75NTR at the plasma membrane of living neuronal cells by single-molecule imaging and tracking. To this purpose we exploit the acyl carrier peptide and some of its shortened versions (A1 and S6 tags, labeled selectively by two different PPTases) to tag human p75NTR and TrkA. These tags were covalently conjugated to the biotin- or fluorophore-substituted arm of a coenzyme A (CoA) substrate.This approach allows: (i) a precise control of stoichiometry and site of biotin conjugation; (ii) versatility of the tags used; (iii) studying two interacting molecules with orthogonal fluorolabels, at the single-molecule or single-interaction-complex level. This experimental toolbox is completed by fast microscopy (e.g. TIRF microscopy with a fast EM-CCD), and by a semi-automatic algorithm for the analysis of the trajectories. This novel algorithm separates self-similar from multimodal trajectories, divides the last ones in subtrajectories, and calculates the combined distributions of parameters measuring the diffusivity, the localization or driftness degree, and/or the number of molecules in tracked spots.We shall present results on the early response of TrkA upon binding different biologically-relevant ligands (including NGF and proNGF): without ligands, TrkA is present mostly as fast-diffusing monomers; ligand binding results in an increasing number of dimers and oligomers, which are typically slower and/or more confined. Each ligand promotes distinct trajectory patterns at the cell membrane, because of different receptor-binding affinities, intracellular effectors recruited and formation of signalling/recycling endosome precursors.We believe that this imaging toolbox and our results pave the way to the quantitative description of the kinetics, dynamics and stoichiometry of any binary or ternary molecular complex formed upon binding of proNGF or NGF to their receptors.

Aberrant nuclear localization of EBP50 promotes colorectal carcinogenesis in xenotransplanted mice by modulating TCF-1 and β-catenin interactions

Dysregulation of canonical Wnt signaling is thought to play a role in colon carcinogenesis. β-Catenin, a key mediator of the pathway, is stabilized upon Wnt activation and accumulates in the nucleus, where it can interact with the transcription factor T cell factor (TCF) to transactivate gene expression. Normal colonic epithelia express a truncated TCF-1 form, called dnTCF-1, that lacks the critical β-catenin-binding domain and behaves as a transcriptional suppressor. How the cell maintains a balance between the two forms of TCF-1 is unclear. Here, we show that ERM-binding phosphoprotein 50 (EBP50) modulates the interaction between β-catenin and TCF-1. We observed EBP50 localization to the nucleus of human colorectal carcinoma cell lines at low cell culture densities and human primary colorectal tumors that manifested a poor clinical outcome. In contrast, EBP50 was primarily membranous in confluent cell lines. Aberrantly located EBP50 stabilized conventional β-catenin/TCF-1 complexes and connected β-catenin to dnTCF-1 to form a ternary molecular complex that enhanced Wnt/β-catenin signaling events, including the transcription of downstream oncogenes such as c-Myc and cyclin D1. Genome-wide analysis of the EBP50 occupancy pattern revealed consensus binding motifs bearing similarity to Wnt-responsive element. Conventional chromatin immunoprecipitation assays confirmed that EBP50 bound to genomic regions highly enriched with TCF/LEF binding motifs. Knockdown of EBP50 in human colorectal carcinoma cell lines compromised cell cycle progression, anchorage-independent growth, and tumorigenesis in nude mice. We therefore suggest that nuclear EBP50 facilitates colon tumorigenesis by modulating the interaction between β-catenin and TCF-1.

Tuning Proton Behavior in a Ternary Molecular Complex

The multicomponent ternary complex of 4-dimethylaminobenzoic acid (4-DABA), 3,5-dinitrobenzoic acid (3,5-DNBA), and 4,4′-bipyridine (BIPY) has been studied by variable temperature X-ray and neutron diffraction. Proton disorder is observed within the 4-DABA homodimers present and quantitatively evaluated from neutron data. The effect of the crystal environment and in particular the pyramidalization of the nitrogen atom within the 4-DABA molecule and the consequential effect on the presence of hydrogen atom disorder are discussed with reference to the previously determined pure 4-DABA structure and the binary cocrystal with 3,5-DNBA.

A possible explanation of the germicide effect of carbon dioxide in supercritical state based on molecular-biological evidence

Supercritical carbon dioxide (CO 2) possesses germicide (bactericide and sporicide) effect. Despite of the fact, that this effect is used in industrial sterilization processes, the sterilization mechanism at molecular level is unclear. Our hypotheses can provide a molecular-biological explanation for the phenomenon. We believe that in supercritical state CO 2 reacts competitively with Met-tRNA fMet, the formation rate and the amount of formyl-methionyl-tRNA (fMet-tRNA fMet) will be diminished by irreversible substrate consumption. The fMet-tRNA fMet possesses a key role in prokaryotic protein synthesis, being almost exclusively the initiator aminoacyl-tRNA. The formed carbamoyl-methionyl-tRNA (cMet-tRNA fMet), probably stable only under pressure and high CO 2 concentration, is stabilized by forming a ternary molecular complex with the GTP-form of the translational initiation factor 2 (GTP-IF2). This complex is unable to dissociate from preinitiation 70S ribosomal complex because of strong polar binding between the protein C-2 domain and the modified initiator aminoacyl-tRNA. The IF2-fMet-tRNA fMet-blocked 70S ribosomal preinitiation complex does not decompose following the GTP hydrolysis, becoming unable to synthesize proteins. The death of the microbial cell is caused by inhibition of the protein synthesis and energetic depletion. Moreover, we propose a possible mechanism for the accumulation of cMet-tRNA fMet in the bacterial cell. Since the translational process is an important target for antibiotics, the proposed mechanism could be a work hypothesis for discovery of new antibiotics. Made by high conservative character of prokaryotic translation initiation, the proposed IF2 pathway deterioration strategy may conduct to obtaining selective (with low mammalian toxicity) antimicrobials and at the same time, with reduced possibility of the drug resistance development.

Robust and sensitive control of a quorum‐sensing circuit by two interlocked feedback loops

The quorum-sensing (QS) response of Vibrio fischeri involves a rapid switch between low and high induction states of the lux operon over a narrow concentration range of the autoinducer (AI) 3-oxo-hexanoyl-L-homoserine lactone. In this system, LuxR is an AI-dependent positive regulator of the lux operon, which encodes the AI synthase. This creates a positive feedback loop common in many bacterial species that exhibit QS-controlled gene expression. Applying a combination of modeling and experimental analyses, we provide evidence for a LuxR autoregulatory feedback loop that allows LuxR to increase its concentration in the cell during the switch to full lux activation. Using synthetic lux gene fragments, with or without the AI synthase gene, we show that the buildup of LuxR provides more sensitivity to increasing AI, and promotes the induction process. Elevated LuxR levels buffer against spurious variations in AI levels ensuring a robust response that endows the system with enhanced hysteresis. LuxR autoregulation also allows for two distinct responses within the same cell population.

Molecular Assembly and Photophysical Properties of Quaternary Molecular Hybrid Materials with Chemical Bond

In this paper, two long chain aliphatic carboxylic acids (oleic acid [OLA] and stearic acid [STA]) are modified with cross-linking molecules (N-2-aminoethyl-3-aminopropyl-methyl-dimethoxylsiliane, (AEAPMMS, H(2) N(CH(2))(2)HN(CH(2))(3)SiCH(3)(OCH(3))(2) and 3-aminopropyl-methyl-diethoxylsiliane (APMES, H(2) N(CH(2))(3)SiCH(3)(OC(2)H(5))(2)) resulting in four new kinds of structural molecular bridge OLA (STA)-AEAPMMS (APMES). Subsequently, ternary molecular complex systems with four molecular bridges OLA (STA)-AEAPMMS (APMES) and 2,2-bipyridyl (bipy) of lanthanides (terbium and europium) or zinc ions were assembled, which resulted in four novel kinds of quaternary molecular hybrid materials (named as bipy-Ln (Zn)-OLA (STA)-AEAPMMS (APMES) with strong chemical bonds (N-Ln(Zn)-O coordination bonds and Si-O covalent bonds) after a sol-gel (cohydrolysis and copolycondensation) process of the modified molecular bridges (as structural ligand) with inorganic precursor (tetraethoxysilane, TEOS). And especially bipy behaves as functional ligand to sensitize the luminescence of terbium or europium ions through the effective intramolecular energy transfer process, which gives rise to the characteristic emission of metal ions. The design and assembly from structural and functional ligands can help achieve a candidate technology for molecular hybrids.

PROTEIN INTAKE ATTENUATES THE DECLINE IN IGF-I DURING PHYSICAL TRAINING AND CALORIC RESTRICTION

Circulating insulin-like growth factor-I (IGF-I) declines with underfeeding and protein inadequacy. It circulates primarily in a ternary molecular complex (∼88%) consisting of IGF-I, IGF binding protein-3 (IGFBP-3), and the acid labile subunit (ALS). PURPOSE To examine the hypothesis that dietary protein supplementation during underfeeding would attenuate the decline in IGF-1 and ternary complex components. METHODS 35 Marines were randomly divided into a Low Protein (LP) (n = 18; 25±1 yrs. 179±2 cm, 82±2 kg) or High Protein (HP) (n = 17; 25±1 yrs, 182±1 cm, 83±2 kg) group before participating in an 8 day field exercise consisting of sustained physical activity (TDEE ∼17–25 MJ/d) and sleep deprivation. Both diet groups consumed 7.0 MJ and 217 g CHO per day. LP and HP consumed 38 (∼0.5 g/kg) and 80 g (∼1.0 g/kg) protein per day, respectively. Morning blood samples were collected before (T1), mid-way (T2) and after (T3) the training. ANOVA with repeated measures was used for statistical analyses (p ≤ 0.05). RESULTS IGF-I declined (∼51%) over time (T1; 412 ng/ml >T2; 258 ng/ml >T3; 203 ng/ml) and interaction effects revealed that this decline was attenuated in the HP group (T1; 399 ng/ml >T2; 256 ng/ml = T3; 219 ng/ml) vs. the LP group (T1; 424 ng/ml >T2; 260 ng/ml >T3; 190 ng/ml) over the latter half of the study. ALS (T1; 2484 ng/ml >T2; 2058 ng/ml >T3; 1717 ng/ml;∼31%) and IGFBP-3 (T1; 4978 ng/ml >4254 ng/ml >4053 ng/ml) declined 31% and 19%, respectively, during the training, with no group or interaction effects. CONCLUSION Protein supplementation may be beneficial in maintaining circulating concentrations of anabolic growth factors during periods of intense physical training combined with restricted caloric intake.

Copolymerization of methylmethacrylate with styrene using triphenylbismuthoniumylide as radical initiator

AbstractBismuthoniumylide‐initiated radical copolymerization of methylmethacrylate with styrene at 60 ± 0.2°C using dioxane as an inert solvent, follows ideal kinetics (Rp ∝ [ylide]0.5 [MMA]1.0 [sty]1.0), and yields alternating copolymer as evident from NMR spectroscopy. The values of reactivity ratios r1 and r2, calculated from Finemann–Ross method are 0.48 and 0.45, respectively. The system follows ternary molecular complex mechanism. The radical mode of polymerization has been confirmed by ESR spectroscopy and the effect of hydroquinone. The value of activation energy and k/kt are 65.0 KJ mol−1 and 2.5 × 10−5 l mole−1 s−1, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2774–2781, 2001

Alternating Copolymerization of Ethyl Acrylate and α-Methyl Styrene. 2. Kinetic and Mechanism

The formation of the ternary molecular complex composed of α-methylstyrene (α-MS), ethyl acrylate(EA) and diethylaluminum chloride (AlEt 2 CI) in of CH 2 CI 2 were examined by UV spectroscopy. The polymerization rate was first order in monomer concentration. The rate depends linearly on the square root of benzoyl peroxide(BPO) concentration and on the cube root of the AlEt 2 Cl concentration. These results can be explained by a mechanism involving the homopolymerization of a ternary molecular complex.

Polymerization of coordinated monomers. XIX. Kinetic study of the alternating copolymerization of methyl methacrylate with styrene by boron trichloride

AbstractAlternating copolymerizations of methyl methacrylate with styrene in the presence of boron trichloride at 0°C in 1,2‐dichloroethane were carried out by using benzoyl peroxide as an initiator. Conversion increased proportionally with polymerization time, whereas the degree of polymerization was constant irrespective of time. The rate depended linearly on the square root of the concentration of benzoyl peroxide. The equilibrium constants for the formation of the ternary molecular complex composed of methyl methacrylate, styrene, and boron trichloride in 1,2‐dichloroethane at −20, −10, and +4°C were determined by 1H‐NMR spectroscopy. The concentrations of the ternary molecular complex in the polymerization mixtures were evaluated from the equilibrium constant of the formation. The rate of the alternating copolymerization was proportional to the first order of the concentration of the ternary molecular complex. The distribution of methyl methacrylate‐centered triads in the alternating copolymer was different from that of styrene‐centered triads. These results can be explained by a mechanism involving the homopolymerization of a ternary molecular complex.

Polymerization of coordinated monomers. XVIII. Sequence distribution in methyl acrylate–styrene copolymers prepared in the presence of zinc chloride

AbstractMethyl acrylate and styrene have been copolymerized in the presence of zinc chloride either by photoinitiation or spontaneously. The copolymerization mechanism is investigated by analyses of copolymers composition and monomer sequence distribution. The resulting copolymers are not always alternating, their composition being dependent especially on the monomer feed ratio. Appreciable deviation to higher methyl acrylate unit content from an equimolar composition occurs at monomer feed fractions of methyl acrylate over 0.7. The larger deviation is induced by higher temperature, by photoirradiation, and by greater dilution of the reaction mixture with toluene. The 13C‐NMR spectrum of the alternating copolymer shows a sharp singlet at the carbonyl region, whereas the spectra of random copolymers prepared by benzoyl peroxide initiation at 60°C show a triplet splitting at the carbonyl carbon region, irrespective of copolymer composition. The relative intensities of the triplet peaks for the random copolymers are in good correspondence to the contents of triad sequences calculated by means of conventional radical copolymerization theory. These results clearly indicate that the carbonyl splitting is caused predominantly by variation of the monomer sequence and not by variation of the stereosequence. The monomer sequence distribution in the copolymers is thus directly and quantitatively measured from the split carbonyl resonance. Although the same triplet splitting appears in the spectra of methyl acrylate–rich copolymers prepared in the presence of zinc chloride at high feed ratios (>0.7) of methyl acrylate, the relative intensities of the split peaks do not fit the sequence distributions of random copolymers calculated by means of the Lewis–Mayo equation. The copolymerization yielding these peculiar sequences and the alternating sequence in the presence of zinc chloride is fully comprehended by a copolymerization mechanism proceeding between two active coordinated monomers, i.e., the ternary molecular complex composed of zinc chloride, methyl methacrylate, and styrene, and the binary molecular complex composed of zinc chloride and methyl methacrylate.

Polymerization of coordinated monomers. XVI. Stereoregulation in the alternating copolymerization of methyl methacrylate with styrene in the presence of metal halides

AbstractTriad cotacticities of alternating copolymers of methyl methacrylate with styrene prepared in the presence of zinc chloride, ethylaluminium sesquichloride, and ethylboron dichloride are investigated from the mechanistic point of view by means of 1H‐ and 13C‐NMR. The cotacticities from 1H‐NMR spectra are obtained accurately by using α‐d‐styrene in the place of styrene and by measuring the spectra on the copolymer in o‐dichlorobenzene at 170°C. The relative intensities of three peaks of the splitting signal for the methoxy protons in the nonalternating copolymers obtained by the use of benzoyl peroxide in the absence of metal halides agree well with the cotacticity distribution calculated theoretically by the Lewis‐Mayo mechanism with the stereoregulation following Bernoullian statistics. The splitting signals in the 1H‐ and 13C‐NMR spectra of the alternating copolymers prepared in the presence of metal halides cannot be explained by the same mechanism. The relative intensities of three peaks of the splitting signals for the methoxy protons and for the carbonyl carbon in the methyl methacrylate unit (the contents of cotactic triads centered by the methyl methacrylate unit) are not equal to those for the aromatic C1 carbon in the styrene unit (the contents of cotactic triads centered by styrene unit). The value of f2Y ‐ 4fxfz is not equal to zero, where fx, fy, and fz are the cosyndiotactic, coheterotactic, and coisotactic triad contents, respectively, in the alternating copolymer. Copolymers obtained in the presence of zinc chloride are not exactly equimolar alternating but always contain a methyl methacrylate unit in excess, and the relative intensities of the three peaks for the aromatic C1 carbon change with the copolymer composition. These results are explained by a proposed mechanism: the alternating copolymerization proceeds through the homopolymerization of a ternary molecular complex composed of a metal halide, methyl methacrylate, and styrene, accompanied with the stereoregulation following first‐order Markovian statistics; the increase of methyl methacrylate content in the copolymer prepared in the presence of zinc chloride is caused by the participation of the binary molecular complex composed of a metal halide and methyl methacrylate in addition to the ternary molecular complex.

On the copolymerization of acrylonitrile with styrene in the presence of Lewis acid, 3. Photoinitiated copolymerization

AbstractThe rate of the acrylonitrile (AN)‐styrene (St) copolymerization (Rp) photoinitiated (λ=365 nm) by the StANZnCl2 complex at 30°C is proportional to the square root of the intensity of radiation. The limiting viscosity number [η] of alternating copolymers increases with the intensity of radiation. The 1/[η] vs. Rp relationship for the StAN copolymers is similar as has been found for the initiation of copolymerization by thermal decomposition of 2,2‐azoisobutyronitrile. Provided benzophenone combined with 2‐propanol is used as a photosensitizer, the rate of the StAN copolymerization in acetone—at constant concentrations of both comonomers, zinc chloride, and benzophenone—decreases with 2‐propanol concentration in the reaction mixture. If benzophenone alone (e.g. without 2‐propanol) is used as a photosensitizer under equal conditions, the observed values of the rate of copolymerization are lower in comparison with the system where the ternary molecular complex is empolyed as a photosensitizer. Moreover, Rp decreases with increasing concentration of benzophenone in the system. These findings are interpreted as a result of the termination reactions of ketyl radicals (hydroxydiphenylmethyl radicals) with macroradicals of copolymer.

Polymerization of coordinated monomers. XIV. Systematic deviations from alternating regulation in copolymerization of methyl methacrylate with styrene in the presence of metal halides

AbstractMethyl methacrylate (MMA) and styrene (St) copolymerize in the presence of zinc chloride at 3°C under photoirradiation. The contents of methyl methacrylate in the copolymers obtained at a [ZnCl2]/[MMA] molar ratio of 0.4 are systematically larger than 53 mole %, which is the limiting value at a small feed ratio of methyl methacrylate. The resulting copolymers are confirmed as the sole products and not the mixtures by thin layer chromatography. The effect of dilution of the monomer feed mixture with toluene on copolymer composition suggests that it depends chiefly on the feed concentration of styrene and hardly at all on monomer feed ratios. Copolymerizations are also conducted in the presence of stannic chloride at −17°C under photoirradiation and in the presence of ethylaluminium sesquichloride at 0°C with spontaneous initiation. The contents of methyl methacrylate in both copolymers obtained at feed ratios lower than 60 mole % almost correspond to the 1:1 alternating copolymer and increase systematically with higher feed ratios. The systematic deviations of copolymer composition obtained in the presence of metal halides are reasonably interpreted by the participation of the binary molecular complex composed of metal halide and methyl methacrylate in the polymerization of the ternary molecular complex composed of metal halide, methyl methacrylate, and styrene.

Polymerization of coordinated monomers. XIII. Binding in the ternary molecular complex composed of γ‐crotonolactone, styrene, and stannic chloride

AbstractThe time‐averaged orientation of the styrene molecule in the ternary molecular complex composed of stannic chloride, γ‐crotonolactone, and styrene is determined by use of 1H‐chemical shifts of the nonequivalent protons of the γ‐crotonolactone. The chemical shift change for each of the various protons of the γ‐crotonolactone on the ternary molecular complex formation can be represented by the anisotropic shielding effect of the benzene ring of one oriented styrene molecule. This fact indicates that the ternary molecular complex has a definite time‐averaged conformation, though the “complexing” styrene molecule exchanges between in the oriented state and in the free state more rapidly than the time scale of the 1H‐NMR spectrometry. The magnitudes of the Coulomb, induction, dispersion, charge‐transfer, and exchange‐repulsion energies between the γ‐crotonolactone and the styrene in the ternary molecular complex are estimated by use of the result of the extended Hückel calculation and that of absorption spectrometry. The Coulomb and dispersion forces between the carboryl group of the coordinated γ‐crotonolactone and the benzene ring of the styrene function mainly in the ternary molecular complex formation. Both the induction force and the charge‐transfer force make a small contribution to the ternary molecular complex formation.

Polymerization of coordinated monomers. XII. Alternating copolymerization of γ‐crotonolactone with styrene with the use of stannic chloride

Abstractγ‐Crotonolactone and styrene copolymerize alternately in the presence of stannic chloride at ‐10°C under photoirradiation. The intrinsic viscosity of the resulting copolymer is in the range of 0.6–0.8 dl/g at 30°C in chloroform. The equilibrium constants for the complex formation between stannic chloride and γ‐crotonolactone were determined in 1,2‐dichloroethane‐toluene solution at 0 and −20°C by use of absorption band at 350 nm. Continuous variation plots based on the 1H‐chemical shift show a 1:1 interaction between styrene and the γ‐crotonolactone coordinated to stannic chloride. The equilibrium constants for the ternary molecular complex formation between the coordinated γ‐crotonolactone and styrene were determined in 1,2‐dichloroethane in the temperature range from −20 to 0°C. The equilibrium constants, derived independently from the measurements of the nonequivalent protons in γ‐crotonolactone, are equal to each other within the experimental error. The mechanism of the alternating copolymerization of γ‐crotonolactone and styrene in the presence of stannic chloride is discussed in terms of the homopolymerization of the ternary molecular complex.

Polymerization of coordinated monomers. XI. Structure and reactivity of the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene

AbstractThe time‐averaged orientation of styrene in the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene was determined by use of the chemical shift changes of the protons in the methyl methacrylate on the ternary molecular complex formation. The observed chemical shift change for each of the protons in the methyl methacrylate is expressed by the weighted average of the shifts due to the anisotropic shielding of the benzene ring of styrene for conformations I and II, using the common statistical weight. Conformations I and II correspond to the cis and trans rotational isomers, respectively, of methyl methacrylate with respect to the rotation of the methoxymethyl group around the carbonyl carbon‐ether oxygen bond. Extended Hückel calculations were made on the methyl methacrylate monomer coordinated to stannic chloride and styrene monomer as well as the growing radicals corresponding to the monomers. The energy levels of the frontier orbitals of the species were determined by use of the ionization potentials, the absorption maxima, and the results of the extended Hückel calculations. The high reactivity of the ternary molecular complex is discussed in terms of the interactions between the frontier orbitals of the styrene and those of the coordinated methyl methacrylate.

Polymerization of coordinated monomers. X. Kinetic study of alternating copolymerization of methyl methacrylate and styrene with stannic chloride in dichloroethane

AbstractThe alternating copolymerization of methyl methacrylate with styrene with the use of stannic chloride was kinetically examined at −20°C in 1,2‐dichloroethane both under photoirradiation and with radical initiator (2:1 tri‐n‐butylboron‐benzoyl peroxide system). At conversions lower than 7%, the conversion increases linearly to the polymerization time, whereas the degree of polymerization is constant irrespective of the polymerization time. The alternating copolymerizations are 1.5 order and the 1.0 order reactions with respect to the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The linear dependences of the rates upon the 0.5 order of the intensity of the incident light and upon the 1.0 order of the concentration of tri‐n‐butylboron indicate a bimolecular termination. The rate normalized by the 1.5 order of the concentration of the coordinated methyl methacrylate and the rate normalized by the concentration of the coordinated methyl methacrylate are proportional to the 1.5 and 1.0 orders of the charged concentration of styrene, for the copolymerizations under photoirradiation and with initiator, respectively. The kinetic results in the 1,2‐dichloroethane solution are quite consistent with those in the toluene solution. The alternating copolymerization mechanism, in which the ternary molecular complex predominantly homopolymerizes as a monomer unit, is confirmed.

Polymerization of coordinated monomers. IX. Charge‐transfer spectrum of the system composed of metal halide, polar vinyl monomer, and electron‐donating monomer

AbstractThe 1:2 stannic chloride–methyl methacrylate complex, the 1:2 stannic chloride–acrylonitrile complex, the ethylaluminum dichloride–methyl methacrylate complex, and the ethylaluminum dichloride–acrylonitrile complex exhibit charge‐transfer absorption bands in the wavelength region longer than 300 nm with electron‐donating compounds such as mesitylene, styrene, toluene, and butadiene. The absorption spectrum of the mixture of either methyl methacrylate or acrylonitrile with the electron‐donating compound is, however, a superpostion of the spectra of the components without any additional absorption. Methyl isobutylate, 3‐butenyl methyl ketone, and propionitrile show no charge‐transfer absorption bands with the electron‐donating compound, even in the presence of a metal halide. Both the presence of the C‐C double bond conjugating with the polar group and the coordination of the polar group to a metal halide are essential for an electron‐accepting monomer to exhibit a charge‐transfer absorption with the electron‐donating compound. Continuous variation plots with the use of the charge‐transfer band definitely show a 1:1 interaction between the methyl methacrylate coordinated to stannic chloride and styrene, resulting in the determination of the equilibrium constants for the charge‐transfer complex formation in methylene chloride: 0.21 l./mole at 25°C and 0.67 l./mole at −50°C. The charge‐transfer absorption is attributed to a ternary molecular complex composed of a metal halide, a polar vinyl monomer, and an electron‐donating monomer.