Multiple Hydrogen Bond Acceptors Research Articles

Antifouling and Self-Healing Performance of Marine Coatings Based on Hydrogen-Bond Interactions.

Biofouling is an urgent problem that has to be solved in marine industries. As the traditional antifouling coating loses its antifouling ability after being damaged, the introduction of self-healing performance into the antifouling coating becomes a high priority. Accordingly, we report here a self-healing and antifouling polyurethane composite coating (PCL/MPU-Si/M) with the use of its carbonyl groups as multiple hydrogen bond acceptors. Its fabrication is carried out under mild and solvent-free conditions, forming a "cross-linking" network structure composed of alternately strong and weak bonds based on multiple carbonyl groups. The self-healing efficiency of PCL/MPU-Si/M in tensile strength is 85% after 48 h at room temperature, and higher temperatures can accelerate this self-healing process. Lubricant polydimethylsiloxane and antifoulant medetomidine endow the material with antifouling properties. The maximum antibacterial ability and algae inhibition coverage ability are 91.7 and 90.9%, respectively. This work provides a possible perspective for the design of antifouling and self-healing marine coatings.

Janus-Type ESIPT Chromophores with Distinctive Intramolecular Hydrogen-bonding Selectivity.

Excited-state intramolecular proton transfer (ESIPT)-based solid luminescent materials with multiple hydrogen bond acceptors (HBAs) remain unexplored. Herein, we introduced a family of Janus-type ESIPT chromophores featuring distinctive hydrogen bond (H-bond) selectivity between competitive HBAs in a single molecule. Our investigations showed that the central hydroxyl group preferentially forms intramolecular H-bonds with imines in imine-modified 2-hydroxyphenyl benzothiazole (HBT) chromophores but tethers the benzothiazole moiety in hydrazone-modified HBT chromophores. Imine-derived HBTs generally exhibit higher fluorescence efficiency, while hydrazone-derived HBTs show a reduced overlap between the absorption and fluorescence bands. Quantum chemical calculations unveiled the molecular origins of the biased intramolecular H-bonds and their impact on the ESIPT process. This Janus-type ESIPT chromophore skeleton provides new opportunities for the design of solid luminescent materials.

Janus‐Type ESIPT Chromophores with Distinctive Intramolecular Hydrogen‐bonding Selectivity

AbstractExcited‐state intramolecular proton transfer (ESIPT)‐based solid luminescent materials with multiple hydrogen bond acceptors (HBAs) remain unexplored. Herein, we introduced a family of Janus‐type ESIPT chromophores featuring distinctive hydrogen bond (H‐bond) selectivity between competitive HBAs in a single molecule. Our investigations showed that the central hydroxyl group preferentially forms intramolecular H‐bonds with imines in imine‐modified 2‐hydroxyphenyl benzothiazole (HBT) chromophores but tethers the benzothiazole moiety in hydrazone‐modified HBT chromophores. Imine‐derived HBTs generally exhibit higher fluorescence efficiency, while hydrazone‐derived HBTs show a reduced overlap between the absorption and fluorescence bands. Quantum chemical calculations unveiled the molecular origins of the biased intramolecular H‐bonds and their impact on the ESIPT process. This Janus‐type ESIPT chromophore skeleton provides new opportunities for the design of solid luminescent materials.

Insight into the role of pseudo-halides as multiple hydrogen bond acceptors in the formation of supramolecular 1D assembly of di and trinuclear zinc complexes

In this manuscript we report the synthesis of two new zinc(II) complexes, [(DMSO)2 ZnL1Zn(NCS)2] (1), and [{(N3)ZnL2}2Zn(DMSO)2] (2) that were characterized by elemental and spectral analyses {H2L1 is 2,2-dimethyl-1,3-propanediylbis(iminomethylene)bis(phenol), and H2L2 is 1,2-propanediylbis(iminomethylene)bis(4-chlorophenol)}. The structures have been confirmed by single crystal X-ray diffraction analysis. Both complexes form 1D supramoelcular assemblies where the pseudohalides act as multiple H-bond acceptors (CH•••S,N and NH•••S,N). These assemblies have been analyzed theoretically using DFT calculations, and the energy associated to each contact has been estimated using the quantum theory of atoms-in-molecules. The importance of long-range van der Waals interactions is emphasized. This manuscript, where two new complexes are synthesized and the H-bonding contacts individually estimated, is expected to attract the attention not only of synthetic inorganic chemists, but also theoreticians and chemists working in crystal engineering and supramolecular chemistry.

Hydrate frameworks involving the pyridazino[4,5-d]pyridazine unit as a multiple hydrogen-bond acceptor

1,4,5,8-Tetramethylpyridazino[4,5-d]pyridazine trihydrate, C(10)H(12)N(4) x 3 H(2)O, (I), and 1,2,3,6,7,8-hexahydrocinnolino[5,4,3-cde]cinnoline tetrahydrate, C(12)H(12)N(4) x 4 H(2)O, (II), exhibit exceptional functionality of the condensed N(4)-heteroaromatic frame as a symmetric acceptor of four hydrogen bonds [N...O = 2.843 (2)-2.8716 (10) A]. Thus, all the N atoms of the electron-deficient and highly pi-acidic polynitrogen heterocycles function as lone-pair donors. In (I), all the molecular components lie on or across special positions; the site symmetry is 2/m for the organic and m2m and m for the two water molecules. In (II), the organic polycycle lies across a crystallographic inversion center. Both structures involve a hydrogen-bonded centrosymmetric water-pyridazine dimer as the basic supramolecular unit, which is integrated into two-dimensional [in (I)] and three-dimensional [in (II)] hydrate frameworks by hydrogen bonding with the additional water molecules [O...O = 2.744 (2)-2.8827 (19) A]. The hydrate connectivity exists in the form of an (H(2)O)(3) trimer in (I) and as a one-dimensional zigzag (H(2)O)(n) chain in (II).