Department of Chemistry, Faculty of Sciences , Tarbiat Modares University , P.O. Box 14117-13116 , Tehran , Islamic Republic of Iran.
Department of Chemistry, Faculty of Science , Arak University , Arak 38156-8-8349 , Iran.
Inorg Chem. 2018 Sep 17;57(18):11578-11587. doi: 10.1021/acs.inorgchem.8b01611. Epub 2018 Aug 30.
To achieve optimized host-guest interactions, a "cavity functionalization" approach has been applied using two isostructure MOFs, [Zn(OBA)(BPDB)] ·2DMF (TMU-4) and [Zn(OBA)(HDPT)] ·DMF (TMU-34), where HOBA = 4,4'-oxybis(benzoic acid), BPDB = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, and HDPT = 3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine. TMU-4 and TMU-34 are functionalized with azine and dihydro-tetrazine groups, respectively. Both of these functions can act as Lewis basic sites, but only the dihydro-tetrazine function inside the cavities of TMU-34 can act as a hydrogen bond donor site. These frameworks were applied in removal of pollutant dyes. The results indicate that TMU-34 can remove rose-bengal B (RB-B) from aqueous solution much more than TMU-4, through size selective and optimized host-guest interaction mechanisms. We believe that the preferred hydrogen bond interaction between RB-B free phenolate/carboxylate and dihydro-tetrazine hydrogens of TMU-34 is responsible for the drastic enhancement in the adsorption capacity and removal kinetics of TMU-34 rather than TMU-4. Our strategy in this work clearly shows that (i) high surface area and porosity as well as rational decoration of MOF cavities with organic functions are the key methods for highly efficient and fast dye removal and (ii) both adsorption and desorption times can be optimized very fast. Also, optimized interaction between TMU-34 and RB-B is strong and effective, yet not so much that it leads to long desorption time. To the best of our knowledge, this is the first paper on removal of highly toxic rose-bengal B dye from aqueous solutions using MOFs.
为了实现优化的主客体相互作用，采用了“空腔功能化”方法，使用两种同构 MOF，[Zn（OBA）（BPDB）]·2DMF（TMU-4）和[Zn（OBA）（HDPT）]·DMF（TMU-34），其中 HOBA=4,4'-氧双（苯甲酸），BPDB=1,4-双（4-吡啶基）-2,3-二氮-1,3-丁二烯，和 HDPT=3,6-二（吡啶-4-基）-1,4-二氢-1,2,4,5-四嗪。TMU-4 和 TMU-34 分别用嗪和二氢四嗪基团官能化。这两种功能都可以作为路易斯碱性位点，但只有 TMU-34 空腔内的二氢四嗪功能可以作为氢键供体位点。这些骨架被应用于去除污染物染料。结果表明，TMU-34 通过尺寸选择性和优化的主客体相互作用机制，可以从水溶液中去除比 TMU-4 更多的玫瑰红 B（RB-B）。我们认为，RB-B 游离的酚盐/羧酸与 TMU-34 的二氢四嗪氢之间的优先氢键相互作用是导致 TMU-34 吸附容量和去除动力学急剧增强的原因，而不是 TMU-4。我们在这项工作中的策略清楚地表明：（i）高表面积和孔隙率以及 MOF 空腔的有机功能的合理修饰是高效快速去除染料的关键方法；（ii）吸附和脱附时间都可以非常快地优化。此外，TMU-34 与 RB-B 之间的优化相互作用既强又有效，但不会导致脱附时间过长。据我们所知，这是第一篇使用 MOF 从水溶液中去除高毒性玫瑰红 B 染料的论文。
