Synthesis and applications of linear and hoop-shaped polycyclic aromatics containing four-membered rings

Ph.D.Functional π molecules with desirable molecular geometry and electronic structure are of great fundamental interests in organic chemistry and materials science, and electronic devices. This thesis addresses two important issues in the research of functional π molecules: (1) high performance p type organic semiconductors for organic thin film transistors (OTFTs), and (2) a new type of nanobelts with wide potential applications in electronic materials and supramolecular chemistry.Chapter 1 reviews functional π molecules in two aspects. The first part focuses on molecular engineering of acenes for organic semiconductors after a brief introduction of semiconductor materials and OTFTs. Bulky substituents and electron withdrawing groups have been introduced into acenes to modify the framework, hence to increase solubility and stability of larger acenes. Particular attention is paid on acene analogues containing antiaromatic moieties, namely pentalene, indenofluorene and cyclobutadienoid, which tune stability and electronic structures. The second part reviews the synthesis and properties of carbon nanobelts, including the calculation of the ring strain energy, the efforts on the synthetic strategies of various types of carbon nanobelts, and the molecular structures and properties of the successfully synthesized carbon nanobelts.Chapter 2 presents the synthesis, crystal structures and semiconductor properties of new derivatives of bisnaphtho[2',3':3,4]cyclobut[1,2-b:1',2'-i]anthracene (BNCBA). It is found that the π-π stacking of BNCBA in single crystals can be largely modified by alkyl substituting groups of different lengths. In particular, the tetrahexyl derivative exhibits π-π stacking with an unusual zigzag arrangement. The variation of molecular packing also leads to change of charge transport characteristics as found from the theoretical calculation of mobility on the basis of single crystal structures. All of these BNCBA derivatives function as p-type semiconductors in solution processed thin film transistors, and the tetrahexyl derivative exhibits field effect mobility as high as 2.9 cm² / Vs.Chapter 3 details design of cyclacenes and N-heterocyclacenes containing four membered rings and synthetic studies toward them . The Acyloin condensation of diester resulted in the α-hydroxy ketone, which was the key precursor for the condensation with diamino aromatic compounds. The [2+2] cycloaddition between alkenes and trichloroacetyl chloride was conducted to give dichlorocyclobut an one, followed by the condensation with phenylenediamine. However, all these trials on the construction of cyclic products failed in preparing the key precursors containing four-membered rings or the final cyclization.Chapter 4 demonstrates the synthesis of a nitrogen-hetero cyclic backbone through the combination of two matched C-shaped precursors, which can be constrcuted by Diels-Alder reaction. The key condensation succeeded in diluted solution, and the resulted cyclic product showed good stability both in solid state and in solution. The experimental and simulated UV-Vis spectra indicated the transition from the TIPS-TAP unit to the pyrene moiety, demonstrating the interaction between two substructures with widely potential applications. The slightly bent tube with contractive cavity is expected to show selectivity towards various guest molecules.具有理想分子構型及電子結構的功能化共軛分子是有機化學與材料科學及電子器件領域的研究基礎。本論文中包含功能化共軛分子研究領域中的兩個重要方面：（ 1 ）高性能的 p 型有機半導體在有機薄膜晶體管中的應用；（ 2 ）在電子材料及主客體超分子化學中有潛在應用的新型含氮納米帶的合成。第一章了概括了兩個主要部分。第一部分简要介绍半导体材料，有機薄膜晶體管以及并苯类分子在有机半导体中的分子工程。大位阻取代基和吸電子取代基常被用來修飾並苯分子以調節分子骨架，進而改善更大的並苯分子的溶解性及穩定性。含有反芳香性片段如戊搭烯、茚並芴 、環丁二烯的並苯類似物尤為重要，其中的反芳香性片段可以調節分子的穩定性及電子結構。第二部分介紹了碳納米帶的合成及性質，其中包括環張力的計算、不同類型的碳納米帶的合成策略研究，及 目前已合成的 碳納米帶的分子結構及光電性質。第二章介紹了新型二萘並[2',3': 環丁基 [1,2-b:1',2'-i] 蒽 ( 衍生物的合成、晶體結構及其半導體性質。研究表明 BNCBA 在單晶中的 π-π 堆積方式可以通過改變烷基取代基的長度得以調控。尤其是其中四己基 衍生物顯示出了不常見的鋸齒形狀的 π-π 堆疊。基於單晶結構的遷移率的理論計算同時證明了分子排列方式的改變也會引起電荷傳輸性質的變化。本文中所陳述的 BNCBA 衍生物在溶液法薄膜晶體管中均呈現出了 p 型半導體的性質，其中四己基衍生物的場效應遷移率高達 2.9 cm²/ Vs 。第三章描述了含有四元環的環芳烯及氮雜環芳烯的合成研究。我們採用了二酯的偶姻縮合製備 α-羥基環丁酮，作為與二氨基芳香化合物縮合的關鍵反應前體。我們也利用烯烴和三氯乙酰氯的 [2+2] 環化反應制得二氯環丁酮化合物，隨後與苯基二胺進行縮合反應。然而上 述這些構建大環分子的方法在製備含四元環前體或者最終的環化反應時均不適用。第四章闡述了用兩個尺寸匹配的C-型前體構建氮雜環形骨架，其中 C-型前體可用 Diels-Alder 反應構建。關鍵反應縮合環化可以在稀釋的溶液中完成，制得的環形產物在固態及溶液中均很穩定。實驗及模擬的紫外 可見光吸收光譜顯示了從 TIPS-TAP 片段向另一芘片段的躍遷，證明兩個子結構間的相互作用，以致其潛在的應用。我們所得到的輕微彎曲的方形管狀 分子有向內收縮的腔洞，可能會對不同的客體分子有選擇性的超分子作用。Wang, Jinlian.Thesis Ph.D. Chinese University of Hong Kong 2019.Includes bibliographical references.Abstracts also in Chinese.Title from PDF title page (viewed on 7, May 2021)