Ratiometric Luminescent Detection of Organic Amines Due to the Induced Lactam–Lactim Tautomerization of Organic Linker in a Metal–Organic Framework

Abstract

Here we demonstrate that a fluorescent benzothiadiazole (BTD)-conjugated terphenyldicarboxylate (TPDC) linker (denoted as H-ostpdc) has been hybridized by a quinoxaline-2,3-(1H,4H)-dione (QD) moiety possessing lactam-lactim tautomerism, which was further integrated into a robust and porous UiO-68 type zirconium metal-organic framework (MOF UiO-68-osdm) by utilizing the mixed two dicarboxylate struts with the same ligand lengths. The resultant MOF UiO-68-osdm can work as a ratiometric luminescent sensor for visual and selective detection of alkyl amines. Furthermore, it can discriminate secondary alkylamines from other type amine species.

Implementing fluorescent MOFs as down-converting layers in hybrid light-emitting diodes

“…2(b)), which contains an unfunctionalised terphenyldicarboxylate linker and shows excellent stability. 19 Previously, related linkers containing central benzothiadiazole units flanked by two benzoic acid rings have been used to prepare Zr MOFs with UiO-68 topologies to sense picric acid 24 and organic amines, 25 or to photocatalytically degrade mustard gas simulants. 26,27 A selenothiadiazole analogue has also been utilised to photocatalyse dehydrogenative cross-coupling reactions.…”

Dimensionality Control in Crystalline Zinc(II) and Silver(I) Complexes with Ditopic Benzothiadiazole-Dipyridine Ligands

“…On the other hand, introduction of coordinating groups on the benzene ring affords neutral or anionic ligands allowing the formation of luminescent discrete complexes or coordination polymers in which the thiadiazole nitrogen atoms can take part, or not, to the coordination of metal centers [24]. In this respect, 4,7-substituted BTD derivatives with carboxylate or carboxylate containing fragments have been used as divergent anionic linkers towards various metal-organic frameworks (MOFs) which showed, for example, luminescence sensing properties in the presence of water [25], organic amines [26], organic dyes [27] or metal ions [28], while neutral 4,7-di(4-pyridyl-vinyl)-BTD ligands, with vinyl spacers between the pyridine rings and the BTD unit, provided luminescent zinc(II) coordination polymers in the presence of dicarboxylate linkers [29]. Particularly interesting is the direct connection of pyridines on the 4,7-positions of BTD, as it allows the access to the series of ditopic ligands 4,7-di(2-pyridyl)-2,1,3-benzothiadiazol (2-PyBTD), 4,7-di(3-pyridyl)-2,1,3-benzothiadiazol (3-PyBTD) and 4,7-di(4pyridyl)-2,1,3-benzothiadiazol (4-PyBTD) (Scheme 1), the first one having the possibility to act as ditopic bis(chelating) ligand if the BTD nitrogen atoms are involved in coordination.…”

Field-induced mononuclear cobalt(ii) single-molecule magnet (SMM) based on a benzothiadiazole-ortho-vanillin ligand

“…16 It is thus not surprising that BTD has been used over the years as a monotopic 17 or ditopic [18][19][20][21] ligand in coordination chemistry due to the pres-ence of the two sp 2 hybridized nitrogen atoms, although the number of reported transition metal complexes remains rather limited. More recently, the introduction of coordinating groups on the benzene ring afforded various functional ligands providing complexes, in which the thiadiazole unit can be involved or not in the coordination to metal centres, 22 such as luminescent coordination polymers with dicarboxylate-BTD derivatives, [23][24][25][26] 4,7-bis(4′-pyridyl)-BTD, 27 or more recently, mononuclear, binuclear and coordination polymers of Zn(II) and Ag(I) within a series of 4,7-bis( pyridyl)-BTD. 28 A very interesting coordination chelating platform, extensively used in the preparation of functional mono-and polynuclear complexes, is the salen type unit which is derived from the condensation of mono-or diamines with salicylaldehyde or ortho-vanillin.…”