One-Pot Parallel Synthesis of Unclosed Cryptands—Searching for Selective Anion Receptors via Static Combinatorial Chemistry Techniques

Abstract

We present the synthesis of 17 macrocyclic compounds having the structure of so-called unclosed cryptands, acting as anion receptors. These compounds possess amide functions playing the role of hydrogen-bond-donating systems. We have synthesized the presented compounds both by standard methods (using batch conditions) and by static combinatorial chemistry methods, using tetrabutylammonium dihydrogen phosphate as a template, promoting the lariat arm postfunctionalization reaction.

Recent Advances in the Synthesis and Applications of Nitrogen-Containing Macrocycles

“…The search for selective anion receptors via static combinational chemistry was the subject of interest of Jurczak [ 18 ]. Seventeen macrocyclic polyamides having a structure of so-called unclosed cryptands were synthesized ( Figure 4 ).…”

Anion Recognition by a Pincer-Type Host Constructed from Two Polyamide Macrocyclic Frameworks Jointed by a Photo-Addressable Azobenzene Switch

“…The lariat arm, apart from bringing extra hydrogen bond functionality, introduces a steric hindrance to the binding cavity and further pre-organizes the macrocyclic framework [41][42][43][44]. To date, this robust macrocyclic platform has been utilized for the construction of potent and selective anion receptors [41,[45][46][47][48][49], phase transfer catalysts (PTC) [50,51], and closely packed molecular hosts for solid-state stabilization of transient supramolecular assemblies such as water clusters [52][53][54] and S• • • S chalcogen bonds [55]. Recently, we have developed practical and productive methods for the synthesis of these systems, using templated-macrocyclization protocols [48,55,56] and post-macrocyclization incorporation of lariat arms under mild conditions [43,46,47,56,57].…”

“…To date, this robust macrocyclic platform has been utilized for the construction of potent and selective anion receptors [41,[45][46][47][48][49], phase transfer catalysts (PTC) [50,51], and closely packed molecular hosts for solid-state stabilization of transient supramolecular assemblies such as water clusters [52][53][54] and S• • • S chalcogen bonds [55]. Recently, we have developed practical and productive methods for the synthesis of these systems, using templated-macrocyclization protocols [48,55,56] and post-macrocyclization incorporation of lariat arms under mild conditions [43,46,47,56,57]. The latter strategy was utilized in the construction of a sterically crowded pincer-type system [57] acting as anion receptor for mono-and dicarboxylates.…”

Solution and Solid State Studies of Urea Derivatives of DITIPIRAM Acting as Powerful Anion Receptors

“…First of all, neutral anion receptors have generally an advantage over the positively charged systems due to their much higher selectivity, despite the lower stabilities of receptor–anion complexes. These result from the presence of binding groups such as hydrogen bond donors, which allow for the establishment of highly directional interactions with the anion [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Furthermore, the unquestionable advantage of acyclic receptors, compared to their cyclic analogues, is their relatively simpler synthesis due to the lack of a problematic and low-yielding macrocyclization step.…”