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科学家发现吡啶基封端长链寡炔到卡拜中端基效应的消失
作者:小柯机器人 发布时间:2020/11/14 16:33:05

近日,加拿大阿尔伯塔大学教授Rik R. Tykwinski及其研究小组发现随着寡炔到多炔碳链长度的增加,端基效应会逐渐消失。相关论文于2020年11月9日发表在《自然-化学》杂志上。

碳的多样性展现在其多种全碳形式(同素异形体),这些形式具有独特的特性(考虑金刚石,石墨,石墨烯和富勒烯之间的差异)。除了自然来源以外,在通过研究新形式碳而扩大碳化学领域上也有很多机遇。在该工作中,寡炔/多炔的合成被用于模拟尚不了解的卡拜(carbyne)。端基的位阻对寡炔的化学稳定作用,特别是3,5-双(3,5-二叔丁基苯基)吡啶基,是组装一系列稳定的寡炔的关键。

本系列的最后一个成员是至今分离和表征出的最长的单分散多炔,具有24个连续炔单位(48个碳)。紫外-可见光谱以及X射线晶体学分析表明端基会影响寡炔衍生物的性质,但这个效应会随着长度朝着多炔/卡拜极限的增加而消失。例如,紫外-可见光谱、分子对称性清晰表明这些特性从寡炔到多炔(不存在端基效应)的演变。综合这些实验数据可以用来对卡拜的D∞h结构预测进行细化。

附:英文原文

Title: The loss of endgroup effects in long pyridyl-endcapped oligoynes on the way to carbyne

Author: Yueze Gao, Yuxuan Hou, Fernando Gordillo Gmez, Mike J. Ferguson, Juan Casado, Rik R. Tykwinski

Issue&Volume: 2020-11-09

Abstract: The versatility of carbon is revealed in its all-carbon forms (allotropes), which feature unique properties (consider the differences between diamond, graphite, graphene and fullerenes). Beyond natural sources, there are many opportunities to expand the realm of carbon chemistry through the study of new carbon forms. In this work, the synthesis of oligo-/polyynes is used to model the elusive carbyne. The chemical stabilization of oligoynes by sterically encumbered endgroups, particularly the 3,5-bis(3,5-di-tert-butylphenyl)pyridyl group, is key to assemble an extended series of stable oligoynes. The final member of this series is the longest monodisperse polyyne isolated and characterized so far, featuring 24 contiguous alkyne units (48 carbons). Spectroscopic and X-ray crystallographic analysis show that endgroups influence the properties of oligoyne derivatives, but this effect diminishes as length increases toward the polyyne/carbyne limit. For instance, with ultraviolet–visible spectroscopy, molecular symmetry clearly documents the evolution of characteristics from oligoynes to polyynes (in which endgroup effects are absent). The combined experimental data are used to refine predictions for the D∞h structure of carbyne.

DOI: 10.1038/s41557-020-0550-0

Source: https://www.nature.com/articles/s41557-020-0550-0

期刊信息

Nature Chemistry:《自然—化学》,创刊于2009年。隶属于施普林格·自然出版集团,最新IF:21.687
官方网址:https://www.nature.com/nchem/
投稿链接:https://mts-nchem.nature.com/cgi-bin/main.plex