The facile coupling of azobenzene dyes to the quadruply hydrogen-bonding modules 2,7-diamido-1,8-naphthyridine (DAN) and 7-deazaguanine urea (DeUG) is described. The coupling of azobenzene dye 2 to mono-amido DAN units 4, 7, and 9 was effected by classic 4-(dimethylamino)pyridine (DMAP)-catalyzed peptide synthesis with N-(3-dimethylaminopropyl)-N’-ethyl carbodiimide hydrochloride (EDC) as activating agent, affording the respective amide products 5, 8, and 10 in 60–71% yield. The amide linkage was formed through either the aliphatic or aromatic ester group of 2, allowing both the flexibility and absorption maximum to be tuned. Azobenzene dye 1 was coupled to the DeUG unit 11 by Steglich esterification to afford the product amide 12 in 35% yield. Alternatively, azobenzene dye 16 underwent a room-temperature copper-catalyzed azide–alkyne Huisgen cycloaddition with DeUG alkyne 17 to give triazole 18 in 71% yield. Azobenzene coupled DAN modules 5, 8, and 10 are bright orange–red in color, and azobenzene coupled DeUG modules 12 and 18 are orange–yellow in color. Azobenzene coupled DAN and DeUG modules were successfully used as colorimetric indicators for specific DAN–DeUG and DAN–UPy (2-ureido-4(1H)-pyrimidone) quadruply hydrogen-bonding interactions.
本文描述了将偶氮苯染料与四重氢键模块2,7-二氨基-1,8-萘啶(DAN)和7-去氧鸟嘌呤脲(DeUG)轻松耦合的方法。通过经典的4-(二甲氨基)吡啶(DMAP)催化的肽合成,使用N-(3-二甲氨基丙基)-N'-乙基碳酰亚胺盐酸盐(EDC)作为活化剂,将偶氮苯染料2与单氨基DAN单元4、7和9偶联,得到相应的酰胺产物5、8和10,收率为60-71%。酰胺连接通过2的脂肪族或芳香族酯基形成,从而实现了灵活性和吸收最大值的调节。偶氮苯染料1通过Steglich酯化与DeUG单元11偶联,得到产物酰胺12,收率为35%。另外,偶氮苯染料16与DeUG炔基17在室温下进行铜催化的偶氮-炔Huisgen环加成反应,得到三唑18,收率为71%。偶氮苯偶联的DAN模块5、8和10呈亮橙红色,偶氮苯偶联的DeUG模块12和18呈橙黄色。偶氮苯偶联的DAN和DeUG模块成功地用作特定DAN-DeUG和DAN-UPy(2-脲基-4(1H)-嘧啶酮)四重氢键相互作用的比色指示剂。