Novel Azobenzene-Functionalized Polyelectrolytes of Different Substituted Head Groups 2: Control of Surface Wetting in Self-Assembled Multilayer Films

A novel set of light-responsive polyelectrolytes has been developed and studied, to control and tune surface wettability by introducing various types of substituted R head-groups of azo polyelectrolytes in self-assembled multilayer (SAMU) films. As part of a larger project to develop polymer surfaces where one can exert precise control over properties important to proteins and cells in contact, photo-reversibly, we describe here how one can tune quite reliably the contact angle of a biocompatible SAMU, containing a photo-reversible azo chromophore for eventual directed cell growth. The azo polyelectrolytes described here have different substituted R head-group pairs of shorter-ionized hydrophilic COOH and SO₃H, shorter non-ionized hydrophobic H and OC₂H₅, and larger non-ionized hydrophobic octyl C₈H₁₇ and C₈F₁₇, and were employed as polyanions to fabricate the SAMU onto silicon substrates by using the counter-charge polycation PDAC. The prepared SAMU films were primarily characterized by measurement of their contact angles with water. The surface wetting properties of the thin films were found to be dependent on the type of substituted R-groups of the azo polyelectrolytes through their degree of ionization, size, hydrophobicity/hydrophilicity, solubility, conformation, and inter-polymeric association and intra-polymeric aggregation. All these factors appeared to be inter-related, and influenced variations in hydrophobic/hydrophilic character to different extents of aggregates/non-aggregates in solution because of solvation effects of the azo polyanions, and were thus manifested when adsorbed as thin films via the SAMU deposition process. For example, one interesting observation is significantly higher contact angles of 79° for SAMU films of larger octyl R groups of PAPEA-C₈F₁₇ and PAPEA-C₈H₁₇ than for others with contact angles of 64° observed for non-polar R-groups of OC₂H₅ and H. Furthermore, lower contact angle values of 59° for SAMU films with polar R-groups of COOH and SO₃H relative to that of non-polar R-groups are in accordance with their expected order of the hydrophilicity or hydrophobicity. It is possible that the large octyl groups are more effective in shielding the ionic functional groups on the substrate surface, and contributed less to the water drop-molecule interactions with ionic groups of the PDAC and/or AA groups. In addition, higher hydrophobicity of the SAMU films may be due to the incorporation of bulky and hydrophobic groups in these polyelectrolytes, which can produce aggregates on the surfaces of the SAMU films. Through understanding and controlling the complex aggregation behavior of the different substituted R-groups of these azo polyelectrolytes, and hence their adsorption on substrates, it appears possible to finely tune the surface energy of these biocompatible films over a wide range, enhance the photo-switching capabilities of the SAMU films, and tailor other surface properties for the development and application of new devices in diverse areas of microfluidics, specialty coatings, sensors, and biomedical sciences.     

Asymmetric Cyclic Phosphorothonamides Containing Substituted Pyridine

In order to find high-acitivity and low-toxicity pesticidal lead compounds, a type of novel, asymmetric cyclic phosphorothonamides containing substituted pyridine were synthesized via the condensation reactions of 2-chloro-4-substitutedphenyl-5,5-dimethyl-1,3,2-dioxaphosphinane 2-sulfide with 3-aminomethylpyridine. The cis and trans isomers of the products were isolated by column chromatography on silica gel. The structures of the products were characterized by ¹ H NMR, ³¹ P NMR, MS, and elemental analyses. The configuration of 3a was determined by X-ray diffraction analysis. The results of the preliminary bioassay showed that the new compounds possess potential fungicidal activities.     

An Efficient,Basic Resin-Mediated,One-Pot Synthesis of Dithiocarbazates Through Alcoholic Tosylates

A quick and efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various alcoholic tosylates of primary, secondary, and tertiary alcohols, with substituted hydrazines using an Amberlite IRA 400 (basic resin)/CS ₂ system. The reaction conditions are mild with simpler work-up procedures than previously reported methods.     

Synthesis and Characterization of Benzonitrile-Substituted Silyl Ethers

The silyl ethers (siloxanes) Me_{4? x}Si(OC₆H₅CN)_x (x = 1–4) (1–4), O(Si(OC₆H₄CN) (Me)₂)₂ (5), and Me₃Si–O–C₆F₄CN (6) have been synthesized by the reaction of the respective p-hydroxybenzonitriles and chlorosilanes in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) as hydrogen chloride acceptor. All compounds have been fully characterized by CHN-analysis, melting point, IR, Raman, mass spectroscopy, and ¹H, ¹³C, ²⁹Si NMR spectroscopy. Furthermore, the crystal structures of these compounds—with the exception of Me₂Si(OC₆H₅CN)₂, which is a liquid—were determined by X-ray diffractometry.     

N,S-Substituted Dienes from Mono(arylthio)substituted- and S-, S,S-Substituted Dienes

Mono(thio)substituted dienes 1a-1b gave compounds 3a-c and 5d-g with piperazine and piperidine derivatives in dichloromethane. Compounds 8 , 9 , and 10 were obtained from the reactions of perchlorobutadiene ( 6 ) with 1,4-butanedithiol ( 7 ) in ethanol in the presence of sodium hydroxide. Compounds 12a-b , 13a-b were obtained from the reactions of perchlorobutadiene ( 6 ) with allylmercaptan (CH 2 =CH--CH 2 --SH) and mercaptoethanol (HO--CH 2 --CH 2 --SH).     

Synthesis and In Vitro Anti-HIV Activity of Some New Schiff Base Ligands Derived from 5-Amino-4-phenyl-4H-1,2,4-triazole-3-thiol and Their Metal Complexes

New Schiff base ligands (6–9) derived from 5-amino-4-phenyl-4H-1,2,4-triazole-3-thiol 1 and substituted benzaldehydes (2–5) as well as their metal complexes with Cu(II), Fe(II), Au(III), and Mn(II) (12–17) have been synthesized. A new benzothiazole derivative (11) was prepared from coupling of 7 with N-(benzothiazol-2-yl)-2-chloroacetamide 10. Their spectral properties were investigated. The newly designed and synthesized Schiff base ligands and the metal complexes were assayed for anti-HIV-1 and HIV-2 activity by examination of their inhibition of HIV-induced cytopathogenicity in MT-4 cells. Compounds 11 and 16 were found to be the most active inhibitors in cell culture (EC₅₀ = 12.2 μg/mL (SI = 4) and > 2.11 μg/mL (SI = > 1), respectively) against HIV-1, whereas 11 showed inhibition against HIV-2 of EC₅₀ > 10.2 μg/mL with SI = 9, which provided a good lead for further optimization.     

Trityl Salt-Initiated Cationic Polymerization of 1,2-Cyclohexene Oxide: Structural Analyses of the Products

The polymerization of 1,2-cyclohexene oxide was carried out at 0°C in dichloroethane with triphenylmethyl hexafluoroarsenate as the initiator. A typical reaction product (PCHO-1) was analyzed by infrared and nuclear magnetic resonance spectroscopy as well as by gel-permeation chromatography, x-ray diffraction, and differential scanning calorimetry (DSC). The x-ray and DSC data show that PCHO-1 is an amorphous substance. The results of the NMR analyses show that the propagation step in the trityl salt-initiated polymerization obeys Bernoullian statistics with a P_m value of 0.38.     

炔桥联不对称苯基取代双二茂铁衍生物的设计合成和电化学性质

以四苯基环戊二烯酮为起始原料,经过八步连续反应,成功地合成了3个炔桥联不对称五苯基取代双二茂铁衍生物Fc''-C≡C-Fc（1）、Fc''-C≡C-C≡C-Fc（2）和Fc''-C≡C-C≡C-Fc''（3）（Fc''=五苯基二茂铁基,Fc=二茂铁基）。在设计合成双二茂铁衍生物的过程中,首先经过4步反应,制备出已知化合物Fc''-H（4）,再连续进行3步反应,分别得到3个中间化合物Fc''-COCH₃（5）,Fc''-CCl=CHCHO（6）和Fc''-C≡CH（7）,最后利用偶联反应,得到目标化合物1~3。利用X射线单晶衍射和循环伏安法,测定了化合物1、2和5、7的晶体结构,研究了化合物1~7的电化学性质。研究结果表明,分子的C-H…π键相互作用和空间位阻是导致化合物1和2分子中Fc''和Fc基空间排布取向不同的主要原因。当二茂铁的一个环戊二烯环上引入5个苯取代基时,铁中心的氧化还原电位将升高（E_p^a（Fc''-H）=0.658 V,E_p^a（Fc-H）=0.511 V）。与已知化合物Fc-C≡C-Fc（ΔE=0.215 V）和Fc-C≡C-C≡C-Fc（ΔE=0.134 V）相比,化合物1~3的氧化电位差值（ΔE）均有不同程度地提高（ΔE₁=0.236 V;ΔE₂=0.170 V;ΔE₃=0.146 V）。将1与Fc-C≡C-Fc,2与Fc-C≡C-C≡C-Fc和3进行比较发现,当炔桥两端连接不同的基团Fc''和Fc时,其氧化电位差值（ΔE）将明显提高。     

不饱和半夹芯式16e化合物Cp*Ir(S2C2B10H10)与邻、间位取代苯基叠氮的反应性

考虑取代基的位置和电子效应对反应体系的影响, 本文系统地研究了16e化合物Cp^*Ir(S₂C₂B₁₀H₁₀) (1)与邻、间位取代苯基叠氮的反应。研究结果表明：与邻、间位取代苯基叠氮反应均生成苯环邻位碳发生C-H 活化形成C-S 键的金属配合物。这些配合物通过核磁(¹H、¹¹B、¹³C)、红外、质谱、元素分析和单晶结构解析进行了全面地表征。在光照反应结果的基础上, 提出了形成这类产物的自由基机理。