Wechselwirkungen in Kristallen. 98. Mitt. Protonierte Hexamethylmelamin-Salze mit verschiedenen Anionen: Monomeres Tetraphenylborat,dimeres Trifluoracetat und polymeres Chlorid-Dihydrat

Interaction in Crystals. 98. Protonated Hexamethylmelamin Salts with Different Anions: Monomeric Tetraphenylborate, Dimeric Trifluoracetate and Polymeric Chloride-Dihydrate Hexamethylmelamin (2,4,6-tris(dimethylamino)-1,3,5-triazine), on monoprotonation at one of the triazine nitrogens keeps its close to planar skeleton. Its salts with different anions reflect biochemically interesting hydrogen-bridge networks: Crystallization of the hydrochloride from isopropanol solution containing Li^⊕ [B^⊖(C₆H₅)₄], yields “naked” molecular cations, packed in herringbone fashion in between the lattice-dominating bulky, phenyl-shielded and non-protonable tetraphenylborate anions. From trifluoroacetic acid, crystals with sandwich-like subunits connected by hydrogen-bridged anions [F₃CCOO^⊖…︁HOOCCF₃] are obtained. The hydrochloride salt, prepared by adding aqueous HCl to a diethylether solution, crystallizes in stacks of triazinium cation dimers with an intermolecular bridge N^⊕-H…︁Cl^⊖…︁H^⊕N in between chloride-bydrate strands (…︁Cl^⊖…︁HOH…︁O(H)H…︁Cl^⊖…︁). Together, the structures of the three different hexamethyl-melaminium salts further illustrate the influence of anions on the crystallization of protonated nitrogen heterocycles and complement that of counter cation cation solvation in molecular anion salts.     

Wechselwirkungen in Kristallen. 96. Darstellung und Strukturen von Salzen [RnN⊕H…︁NRn][B⊖(C6H5)4] mit Prototyp-Wasserstoffbrücken N⊕H…︁N

Interactions in Crystals. 96. Preparation and Structures of Salts [R_nN^⊕H…︁NR_n][B^⊖(C₆H₅)₄] with Prototype Hydrogen Bridges N^⊕H…︁N Straightforward crystallization of ammonium salts [R_nN^⊕H] X^⊖ added lithium tetraphenylborate, and amine R_nN from acetone solution yields salts [R_nN^⊕H…︁NR_n][B^⊖(C₆H₅)₄] with the (under the conditions) unprotonated anions and the cations with prototype hydrogen bridges N^⊕H…︁N. The structures of both identically substituted R_nN (methylamine, trimethylamine, quinuclidine, diazabicyclooctane, and pyridine) as well as two-component cation species (quinuclidine…︁pyridine and diazabicyclooctane…︁pyridine) are reported and discussed. A Cambridge Structural Database search defines the area of charged N^⊕H…︁N interactions which can be correlated with both pK values and PM3 formation enthalpies. Additional information is provided by PM3 calculations based on the experimental structure coordinates. The charge distribution within the hydrogen bridges N^⊕H…︁N varies considerably with the individual proton donors N⁺H and proton acceptors N: Positive charges are highest at protonated quinuclidine and diazabicyclooctane centers and lowest at pyridine N acceptor centers.     

Darstellung,Tautomerieverhalten und Wasserstoffbrücken-bindung von 2-Heteroarylamino-thiazolen

Synthesis, Tautomeric Properties, and Hydrogen Bonds of 2-Heteroarylamino-thiazoles 2-Heteroarylamino-thiazoles have been prepared by the method of HANTZSCH from heteroaryl-substituted thioureas. UV and IR spectra indicate the amino form for these compounds. In solid state, they are associated through N H…︁N bonds, the nitrogen atom of the thiazole ring serving as an acceptor of protons.     

Synthetic Modifiers for Platinum in the Enantioselective Hydrogenation of Ketopantolactone: A Test for the Mechanistic Models of Ketone Hydrogenation

Various derivatives of (R)‐1‐(1‐naphthyl)ethylamine have been synthesized and tested as chiral modifiers of Pt/alumina in the enantioselective hydrogenation of ketopantolactone. The best modifiers (ee up to 79%) possess an ester function in the α‐position to the amino group. The modifiers performed far better in AcOH than in toluene, indicating that protonation of the N atom is important in enantioselection. The striking non‐linear behaviour of modifier mixtures with cinchonine indicates that the alkaloid adsorbs much stronger on Pt than the naphthylethylamine derivatives. Two mechanistic models are proposed for interpretation of the results, involving an N H O or N⁺ H O bond between the amine‐type modifier and the keto carbonyl O atom of ketopantolactone, in apolar and protic media, respectively. In both cases the H atom originates from the modifier and not from the substrate (“half‐hydrogenated‐state”). The higher ee achieved in acidic medium is attributed to the better proton donor ability of the protonated amine modifiers. The models are applicable also to the hydrogenation of ethyl pyruvate.     

Wechselwirkungen in Kristallen. 76. Einkristallstrukturen von 2,5-Bis(trimethylsilyl)hydrochinon ohne Lösungsmittel sowie mit Dimethoxyethan oder Dioxan: Ein Einblick in die Vielfalt von Wasserstoffbrücken-Bindungen desselben Moleküls

Interactions in Crystals. 76. Single Crystal Structures of 2,5-Bis(trimethylsilyl)-hydroquinone without Solvent and with either Dimethoxyethane or Dioxane: Some Insight into the Manifold of Hydrogen Bridge Bonding of the same Molecule 2,5-Bis(trimethylsilyl)hydroquinone (monoclinic, C2/c, Z=12) forms infinite strings in x-direction, in which alternatingly on both sides each three molecules are bound together by three phenolic H bridges in a triangular arrangement. In the dimethoxyethane solvate (triclinic, P1 , Z=1) with a 3:2 ratio of phenol to ether, the infinite strings are interlinked by twice  OH…︁O bonded H₃COCH₂CH₂OCH₃ chelate molecules. The smallest subunit with only two Hydrogen bonds  OHO…︁(CH₂CH₂)₂O is formed in the monomeric 2:1 dioxane solvate (triclinic, P1 , Z=1). The structural details of the different H bridge bonds are discussed based both on a statistical analysis from the Cambridge Structural Database as well as on PM3-calculated enthalpies of formation starting from the crystal structures determined.     

Zur Rolle von EDA-Komplexen bei kationischen Polymerisationen. VIII. Zur Charge-Transfer-Wechselwirkung von bπ-Donatoren mit organischen Kationen in Lösung

On the Role of EDA-complexes in Cationic Polymerization. VIII. The Charge-Transfer-Interaction of bπ-Donors with Organic Cations in Solution The interaction of 25 aromatic bπ-donors with organic cations of the type (RC₆H₄)₃ C^⊕X^⊖ (R =  CH₃,  C(CH₃)₃,  OCH₃,  H,  Cl,  I,  NO₂; X = BF₄^⊖, AsF₆^⊖, SbCl₆^⊖, FeCl₄^⊖) is investigated by means of u.v.-spectroscopy. The influence of the dissociation on the charge transfer energy will be discussed. With the decreasing concentration of the salt the charge transfer band is hardly shifted at longer wave length. The charge transfer energy can be described as a linear function of structural parameters (i.e. σ_p of R; I_p of the donor and reciprocal radius of the anions, respectively). The influence of the solvent is dependent on both the donicity and dielectric factors.     

Organische Phosphorverbindungen. XIII. Reaktion vinyloger Chlormethylenimmoniumsalze mit Phosphorigsäuretrialkylestern

Organic Phosphorus Compounds. XIII. Reaction of Vinylogous Chloromethylene Immonium Salts with Trialkyl Phosphites 3-Chloropropenylidene immonium salts of the type Cl CArCH CHNMe₂^⊕X^⊖ don't react like chloromethylene immonium salts Cl CHNMe₂^⊕X^⊖ with trialkyl phosphites according to the classical MICHAELIS -ARBUSOV principle (RO)₃P + R′Cl → (RO)₂P(O)R′ + RCl but lead to salts of 1-dimethylaminophosphonates (RO)₂P(O) CH(NMe₂ · HX) CHCClAr the structure of which is confirmed by two independent syntheses. Some characteristic reactions of the free dimethylaminophosphonates are described.     

Synthesis and characterization of new bis(crown ether)s of Schiff base type containing recognition sites for sodium and nickel guest cations

New bis(crown ether) ligands of Schiff base type ( 2 – 4 ) containing recognition sites for sodium and nickel guest cations have been synthesized by the condensation of two equivalents of 4′-formyl-5′-hydroxy(benzo-15-crown-5) ( 1 ) with diamines, H₂N–(CH₂)_n–NH₂(n = 2–4). Homonuclear ditopic crystalline 2 : 1 (Na⁺ : ligand) complexes ( 2a – 4a , 2b – 4b ) of the ligands with NaSCN and NaClO₄ have been prepared. The NaClO₄ complexes of 3 and 4 ( 3b and 4b ) form heteronuclear tritopic crystalline complexes with Ni²⁺ cations of stoichiometry 2 : 1 : 1 (Na⁺ : Ni²⁺ : ligand). A homonuclear monotopic Ni²⁺ complex has also been prepared by the reaction with Ni(CH₃COO)₂ · 6H_2O. The UV-VIS spectra of 2 – 4 and their NaClO₄ complexes ( 2b – 4b ) are studied in different solvents including acidic and basic media. In polar solvents, tautomeric equilibria (phenol–imine, O–H…︁N and ketoamine, O…︁H–N forms) are present, as supported by the UV-VIS data.     

Preparation of silicone containing 2,2,6,6-tetramethyl-4-piperidinol-based N-chloramine for antibacterial polyethylene via interpenetration in supercritical carbon dioxide

Functionalization of polyethylene (PE) with powerful biocides through a friendly and efficient procedure is necessary to obtain extended applications. A novel CO₂-philic 2,2,6,6-tetramethyl-4-piperidinol (TMP)-based N-chloramine silicone was synthesized via Pt-catalyzed silane alcoholysis between the Si H of poly(methylhydrosiloxane) and O H of TMP and followed by chlorination of amine N H originating from TMP to N Cl. The TMP-based N-chloramine silicone was interpenetrated into PE using supercritical carbon dioxide (scCO₂) as working solvent. It was shown that the thickness of the TMP-based N-chloramine silicone layer on PE can be easily controlled by the interpenetration pressure, reaching a maximum value of 70 nm at 28 mp. The synthetic procedures and the interpenetration results were characterized by Fourier transform infrared, scanning electron microscopy, and X-ray photoelectron spectroscopy. In contrast with pristine PE that did not show biocidal ability, the TMP-based N-chloramine silicone modified PE imparted powerful antibacterial abilities, exerting total kills of both Staphylococcus aureus and Escherichia coli of ~10⁷ cfu mL⁻¹ in 30 min. The biocidal functionality was durable toward washings, storage, and ultraviolet exposure and the recoverability of lost chlorines was good. The interpenetration in scCO₂ tactic provides an environmentally friendly and universal approach to functionalize inert substrates due to no needs of harmful solvent and chemical linkages with biocides. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47614.     

Construction of silicone with quaternized hydantoin-based N-chloramines on cotton with aid of supercritical interpenetration for antibacterial synergism

A silicone carrying combined functionalities of different mechanisms and physiochemical properties is synthesized as a strategy for faster and broader bacterial eliminations. Briefly, ring-opening alcoholysis of succinic anhydride with 2-dimethylaminoethanol and subsequent esterification of the alcoholysis product with 5-(4-hydroxyphenyl)imidazolidine-2,4-dione produced a structure with one tertiary amine and two hydantoinyl N H bonds. The tertiary amine was quaternized with 3-chloro-1-propanol whose O H was then alcoholyzed with Si H of poly(methylhydrosiloxane). The polymeric product was interpenetrated into cotton at 30 MPa and 50°C in supercritical CO₂ and treated with tert-butyl hypochlorite to chlorinate its hydantoinyl N H bonds, forming a 78 nm biocidal layer of silicone with quaternized hydantoin-based N-chloramines. Antibacterial tests showed that the quaternary ammonium salt and two hydantoin-based N-chloramines act synergistically due to their complementary features, killing both Staphylococcus aureus and Escherichia coli much more efficiently than each functionality. More importantly, the ratio of N-chloramine to quaternary ammonium salt of 2:1 herein also provided higher efficacy than a reported counterpart with a 1:1 ratio. Biocidability of the modified cotton had promising stability and rechargeability, which indicates that supercritical interpenetration produced a durable interfacial layer without the necessity of chemical bonding.     

Vinyloge Acylverbindungen. XX. Reaktivität und Toxizität arylsubstituierter β-Chlorvinylketone, β-Chlorvinylaldehyde und β-Chlorvinylmethyleniminiumsalze

Vinylogous Acyl Compounds. XX. Reactivity and Toxicity of Aryl-substituted β-Chlorovinyl Ketones, β-Chlorovinyl Aldehydes, and β-Chlorovinyl Methyleniminium Salts Based on kinetic measurements, the nucleophilic replaceability of the chlorine in aromatic β-chlorovinyl ketones ArCO-CH  CH-Cl ( 1 ), isomeric β-chlorovinyl aldehydes OCH CHC(Cl)Ar( 2 ), and corresponding β-chlorovinyl methyleniminium salts Me₂N^⊕;CH CHC(Cl)Ar X^⊖ ( 3 ) is compared and related to toxicological findings. The chemical reactivity of these important synthetic building blocks increases in the order 2 < 1 < 3 , the acute toxicity (24 h LD₅₀ i. p. in the mouse) shows the graduation 2 < 3 < 1 . Compounds of type 1 prove to be relatively toxic (LD₅₀ 24–42 mg/kg) and display a marked necrotic action after percutaneous absorption, whereas the aldehydes 2 have not only a minor acute toxicity (LD₅₀ 158–298 mg/kg) but also a somewhat less marked skin damaging activity. In addition, the LD₅₀ values of selected β-chlorovinyl carbonyl compounds are compared with those of corresponding halogen-free compounds as well as of vinylogous carbonamidium salts ArCO CHCH N^⊕R₃X^⊖. The latter, which can be used as synthetic equivalents of 1 , differ in both the reduced acute toxicity and missing skin damaging properties.     

Synthesis and properties of ultraviolet/moisture dual‐curable polysiloxane acrylates

Ultraviolet (UV)/moisture dual‐curable polysiloxane acrylates (PSAs) were prepared from N,N‐bis[3‐(triethoxysilyl)propyl]amine (G402) and ethoxylated trimethylolpropane triacrylate (EB160) through Michael addition. The obtained prepolymers were characterized by ¹H‐NMR and FTIR. The rheological behavior of the prepolymers exhibited the properties of a Bingham fluid and the apparent viscosity was directly correlated with molecular weight. The photocuring kinetics of PSA were studied using photo‐DSC and all the polymerization conversions were high. With increasing content of tertiary amine in the prepolymer, the photocuring rate in air increased as well. The moisture‐curing kinetics of the prepolymers was studied using FTIR. It was found that the curing mechanism may be described as the transforming of Si O C into Si O Si structure, which was consistent with the theoretical expectation. DSC and TGA were used to characterize the glass‐transition temperatures and the thermomechanical stability of the prepolymers. Measurements of physical properties showed excellent gloss, impact strength, and high electric resistance for both UV‐ and moisture‐cured films, but poor adhesion for UV‐cured films and lower hardness for moisture‐cured films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 846–853, 2005     

Supramolecular structure of the tetrabutylammonium salt of 2-phenylpropionitrile

The deprotonation of 2-phenylpropionitrile Ph(CH₃)CHCN ( 3 ) by n-Bu)₄N⁺(OH)^– results in the corresponding tetrabutylammonium salt ( 4 ) in excellent yield. An X-ray structural analysis shows that the compound is not a genuine carbanion (“naked anion”). Instead, a dimeric form is found in the crystal in which the nitrogen of the cyano group in the anion undergoes multiple H-bonding with the α-methylene units of the (n-Bu)₄N⁺ cations as a consequence of CH…︁N interactions. A cryoscopic study of the compound in benzene indicates the existence of tetramers, which means that in solution supramolecular ions pairs are involved.     

Über die strukturanalystische Anwendung von „anomalen”︁ Multipletts in off-resonance entkoppelten 13C-NMR-Spektren von ?CH  CH?Fragmenten

On the Structural Analytical Application of „Anomalous”︁ Multiplets in Off-resonance Decoupled ¹³C NMR Spectra of  CH  CH Fragments The theoretical background of “anomalous” splitting of signals of molcular fragments  CHCH in off-resonance decoupled ¹³C NMR spectra is described. The use of these splitting phenomena on the determination of vicinal H,H and geminal C,H coupling constants is demonstrated using simple examples. The possibilities to determine the configuration of double bonds are shown by other examples from the field of natural constituents chemistry.     

Determination of the Dipole Moment of the Charge-Shift Triplet Exciplex from zinc phthalocyanine tetrasulfomorpholide and p-methoxy-benzenediazonium tetrafluoroborate

Triplet exciplexes are known to have usually relatively low polarities, in contrast to singlet exciplexes. It is shown that triplet quenching rate constants of the title system can be used to determine the exciplex dipole moment if it is (plausibly) assumed that the dissociation rate constants of charge-shift exciplexes only depend on the viscosity but not on the polarity of the solvent. The quenching rate constants k_q of the title system in various acetonitrile/acetone or acetonitrile/ethylacetate mixtures are determined and treated by an adapted McRAE equation developed for UV-VIS absorption spectroscopic data. The dipole moment of p-methoxy-benzenediazonium tetrafluoroborate necessary for the solution of the McRAE equation is estimated by a Hammett correlation of known data which gives by extrapolation μ(p-MeO C₆H₄N₂^⊕BF₄^⊖) = 31.4 × 10⁻³⁰ Cm (9.4 Debye). Using this value and a cavity radius of 3.7 × 10⁻¹⁰m (cp. [1]) μ_ex³(ZnPcTSM…p-MeO–C₆H₄N₂^⊕BF₄^⊖)* = 16.0 × 10⁻³⁰ cm (4.8 Debye) is obtained. According to this value the triplet exciplex studied has a lower polarity than the starting diazonium salt.     

Polysulfobetaines and corresponding cationic polymers. VI. Synthesis and aqueous solution properties of cationic poly(methyl iodide quaternized acrylamide–N,N-dimethylaminopropylmaleimide copolymer) [poly(MIQADMAPM)]

The copolymer prepared by copolymerizing with acrylamide and maleic anhydride was imidized with N,N-dimethylaminopropylamine. The obtained acrylamide–N,N-dimethylaminopropylmaleimide (ADMAPM) copolymer was then reacted with methyl iodide to yield a poly(methyl iodide quaternized acrylamide–N,N-dimethylaminopropylmaleimide) copolymer [poly(MIQADMAPM)]. Its aqueous solution properties were studied by measurements of reduced viscosity, intrinsic viscosity, and flocculation test in this study. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentration of the added salt. “Soft” salt anions were more easily bound to the quaternary ammonium cation (R₄N⁺) of poly(MIQADMAPM) than were “hard” salt anions. Halide anions are hard anions; consequently, hard cations were more easily attracted to halide anions and reduced the binding degree of halide anion on the quaternary ammonium group (R₄N⁺). The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain was contrasted with polyampholyte. The effect of various flocculants on flocculation in different pH values was accessed in this study. © 1996 John Wiley & Sons, Inc.     

Structure and Properties of Cocrystals of Phenazine and Fumaric‐, 2,3‐Dihydroxyfumaric‐, and Oxalic Acid

Phenazine and the dicarboxylic acids fumaric‐, 2,3‐ dihydroxyfumaric‐, and oxalic acid form 1 : 1 cocrystals. X‐ray analysis shows that the molecules are arranged as linear tapes, mainly held together by strong O‐H…︁N and weak C(sp ²)‐H…︁O hydrogen bonds. Individual molecules form staples which are surrounded by staples of the other molecules. The angle between neighbouring tapes varies from ca. 90° in the cocrystal of phenazine and fumaric acid to ca. 70° in the co‐crystal of phenazine and 2,3‐dihydroxyfumaric acid, and ca. 25° in the cocrystal of phenazine and oxalic acid. The molecules assume an offset face‐to‐face arrangement in individual phenazine staples. Negligible π‐stacking is observed in the cocrystals of phenazine with fumaric‐ and 2,3‐dihydroxyfumaric acid. The absence of the CC double bond as spacer in oxalic acid leads to appreciable π‐overlap of phenazine molecules in the cocrystal. As a consequence, the latter cocrystal displays special properties. An irreversible lightinduced electron transfer generates initially singlet and triplet biradicals with the unpaired electrons positioned on neighbouring phenazine molecules. Partially, the electrons are transformed to magnetically independent electrons which show strong exchange narrowing in the e.p.r. spectrum at temperatures > 0 °C. The proposed model is supported by UV/Vis‐e. s.r.‐, and SQUID measurements.     

Chelation of chitosan derivatives with zinc ions. II. Association complexes of Zn2+ onto O,N‐carboxymethyl chitosan

The chelation of zinc ions onto O,N‐carboxymethyl chitosan (ONCMCh) was characterized using a Fourier transform infrared (FTIR) spectrophotometer and a scanning electron microscope (SEM). From the FTIR spectra, little change in the absorption intensities and frequencies at 3300–3600 cm⁻¹ of Zn²⁺ ONCMCh chelated specimens suggested that  OH and  NH₂ groups were not participating in the chelation reaction. The absence of absorption bands at 1755–1700 cm⁻¹ suggested that the carboxyl group CO was not ionized, and the ionized CO bands were observed at 1400–1600 cm⁻¹ for chelated specimens. Thus, the chelation sites took place at the carboxyl group rather than at the  OH and NH₂ groups. It also confirmed that water‐insoluble chelates, which were formed through the Zn O and Zn N bonds, presented a tetrahedral structure. The water‐soluble complexes where zinc ions connected with oxygen of CO and water molecules were only due to electron attraction. Formation of different microstructures on the surfaces, as revealed by SEM, provided evidence to distinguish different chelating mechanisms between water‐soluble and water‐insoluble complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1476–1485, 2001     

Synthese und UV-spektroskopische Charakterisierung von Carbeniumionen an Aerosil

Synthesis and UV-spectroscopic Characterization of Carbenium Ions on Aerosil The interaction of aerosil with various triphenylmethyl derivatives in the cationic vinyl polymerization in 1,2-dichloroethane was studied. The adsorption of the triphenylmethylium ions onto aerosil surfaces strongly depends on both the type of substituents (R   CH₃,  OCH₃,  Cl,  H and  NO₂) and the nature of the counter anion (SbCl₆^⊖, FeCl₄^⊖, SnCl₅^⊖, HSO₄^⊖, SO₄^2⊖, F^⊖, Cl^⊖, Br^⊖, CF₃COO^⊖, N₃^⊖ and SCN^⊖). The binding of the triphenylmethylium ions with aerosil occurs via nucleophilic anions such as halides. Counter anions derived from metal halides as MtX_n+1^⊖ are not able bind on aerosil. Covalent compounds as triphenylmethyl halides are ionized by the acidic aerosil surface. The influence of substituents at the triphenylmethylium ion, the type of counter anions and the influence of water traces on surface — ionization are discussed.     

Synthesis and Characterization of Energetic 1,2‐Bis(Oxyamino)Ethane Salts

The synthesis, characterization, theoretical calculations, and safety studies of energetic salts based on 1,2‐bis(oxyamino)ethane, (H₂N O CH₂ CH₂ O NH₂), were carried out. The salts were characterized by vibrational (infrared, Raman), multinuclear NMR studies (¹H, ¹³C), differential scanning calorimetry (DSC), elemental analysis, and initial safety testing (impact and friction sensitivity). Single crystal X‐ray diffraction studies were carried out on the mono‐perchlorate and the double nitrate salts, revealing the expected structures.