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首页> 外文期刊>Chemistry: A European journal >Remarkable Regioisomer Control in the Hydrogel Formation from a Two-Component Mixture of Pyridine-End Oligo(p-phenylenevinylene)s and N-Decanoyl-l-alanine
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Remarkable Regioisomer Control in the Hydrogel Formation from a Two-Component Mixture of Pyridine-End Oligo(p-phenylenevinylene)s and N-Decanoyl-l-alanine

机译：吡啶末端低聚（对亚苯基亚乙烯基）和N-癸酰基-1-丙氨酸两组分混合物在水凝胶形成中的显着区域异构体控制

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摘要

N-Decanoyl-l-alanine (DA) was mixed with either colorless 4,4'-bipyridine (BP) or various derivatives such as chromogenic oligo(p-phenyl-enevinylene) (OPV) functionalized with isomeric pyridine termini in specific molar ratios. This mixtures form salt-type gels in a water/ethanol (2:1, v/ v) mixture. The gelation properties of these two-component mixtures could be modulated by variation of the position of the "N" atom of the end pyridyl groups in OPVs. The presence of acid-base interactions in the self-assembly of these two-component systems leading to gelation was probed in detail by using stoichiometry-dependent UV/Vis and FTIR spectroscopy. Furthermore, temperature-dependent UV/Vis and fluorescence spectroscopy clearly demonstrated a J-type aggregation mode of these gelator molecules during the solto-gel transition process. Morphological features and the arrangement of the molecules in the gels were examined by using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the XRD patterns revealed that this class of gelator molecules adopts lamellar organizations. Rheological properties of these twocomponent systems provided clear evidence that the flow behavior could be modulated by varying the acid/amine ratio. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and XRD results revealed that the solid-phase behavior of such two-component mixtures (acid/base= 2:1) varied significantly upon changing the proton-acceptor part from BP to OPV. Interestingly, the XRD pattern of these acid/base mixtures after annealing at their associated isotropic temperature was significantly different from that of their xerogels.
机译：将N-癸酰基-1-丙氨酸（DA）与无色4,4'-联吡啶（BP）或以特定摩尔比官能化的异构衍生物吡啶末端官能化的各种衍生物，例如发色低聚（对苯基亚乙烯基）（OPV） 。该混合物在水/乙醇（2：1，v / v）混合物中形成盐型凝胶。可以通过改变OPVs中末端吡啶基的“ N”原子的位置来调节这些两组分混合物的胶凝特性。通过使用依赖于化学计量的UV / Vis和FTIR光谱，详细探讨了导致凝胶化的这两种组分系统自组装中酸碱相互作用的存在。此外，温度依赖性的UV / Vis和荧光光谱清楚地证明了这些胶凝剂分子在溶胶-凝胶转变过程中的J型聚集模式。通过使用扫描电子显微镜（SEM），原子力显微镜（AFM）和X射线衍射（XRD）技术检查了凝胶中分子的形态特征和排列。通过扩展构象中的能量最小化来计算每个分子系统的长度，并与XRD图进行比较，结果表明这类胶凝剂分子采用层状组织。这两种组分系统的流变性质提供了明确的证据，表明可以通过改变酸/胺比来调节流动行为。偏光显微镜（POM），差示扫描量热法（DSC）和XRD结果表明，当从BP改变质子受体部分时，这种两组分混合物（酸/碱= 2：1）的固相行为发生了显着变化。到OPV。有趣的是，这些酸/碱混合物在相关的各向同性温度下退火后的XRD图谱与干凝胶的XRD图谱明显不同。

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