Molecular structure, hydrogen bonding, basicity and spectroscopic properties of N,N′-dimethylpiperazine betaines and their hydrohalides

Unusual 2:3:2 complex of DABCO mono-betaine with HCl and H2O studied by X-ray diffraction, DFT calculations and spectroscopic methods

“…Similarly as 1,4-dimethylpiperazine [18], 1,4-diazabicyclo[2.2.2]octane (DABCO) forms two betaines: DABCO mono-betaine [36] and DABCO di-betaine [34]. 1,4-Dimethylpiperazine mono-betaine (MBPZ) has two non-equivalent proton-acceptor centers and forms a crystalline complex with two molecules of HCl or HBr, while 1,4-dimethylpiperazine di-betaine (DBPZ) has two equivalent proton-acceptor centers and forms the complex with one molecule of HCl.…”

Physio-Chemical Properties of Piperazinediium bis(4-Nitrophenolate)dihydrate: A Non-linear Optical Crystal

“…The piperazine ring is frequently used as a building block for pharmaceuticals [14,15]. Recently it has been found that some polycationic ligands, including piperidine and piperazine rings, exhibit a substantial degree of selective RNA binding [16]. The base piperazine is an electron donor and p-nitrophenol is an electron acceptor compound.…”

Supramolecular structure of the 1:2 complex of 1,4-dimethylpiperazine mono-betaine with squaric acid

“…(7). The complex of MBPZ with squaric acid (H 2 SQ), (1), was prepared by mixing 0.54 g of MBPZ dissolved in 2 ml of methanol with 0.69 g of H 2 SQ dissolved in 2 ml of water.…”

“…N-alkylation reactions of piperazine and 1,4-dimethylpiperazine yield symmetrically and asymmetrically substituted derivatives. The reaction pathway depends on the reaction conditions (2)(3)(4)(5)(6)(7). Recently, we have studied hydrogen-bonded complexes of 1-carboxymethyl-1,4-dimethylpiperazinium inner salt (1,4-dimethylpiperazine mono-betaine, MBPZ) and 1,4-dicarboxymethyl-1,4-dimethylpiperazinium inner salt (1,4-dimethylpiperazine di-betaine) with HCl (7), p-hydroxybenzoic acid (8,9), 3-iodobenzoic acid (10) and L-and meso-tartaric acids (11)(12)(13).…”

“…MBPZ has two different proton -acceptor centres, the carboxylate group (pK 1 ¼ 1.48) and the tertiary nitrogen atom (pK 2 ¼ 4.90) (7), whereas H 2 SQ is a strong acid characterised by two dissociation constants, pK 1 ¼ 1.2 -1.7 and pK 2 ¼ 3.2-3.5 (15 -17). H 2 SQ by transferring one proton to a base generates a hydrogen squarate anion, HSQ 2 , or by transferring two protons it can generate a squarate dianion, SQ 22 .…”