Language：English   Publishing type：Research paper (scientific journal)  

Ring-opening polymerization (ROP) of monofunctional neopentylglycol carbonate (NPGC) with or without bifunctional di(trimethylolpropane) carbonate (DTMPC), which are derived from available corresponding alcohols, affords linear polycarbonates or covalently-linked polycarbonate networks, respectively. A series of available ethanol amine derivatives having the different numbers of 2-hydroxylethyl arms (N, N, N', N'-tetrakis(2-hydroxyethyl) ethylenediamine, triethanolamine, N-methyldiethanolamine or N, N-dimethylethanolamine) initiates the ROP of NPGC to afford star-shaped, telechelic, or linear polycarbonates bearing tertiary amines with well-controlled molecular weights and relatively narrow polydispersities Furthermore, the copolymerization of NPGC and DTMPC in the presence of these initiators readily gives tertiary amine-modified polycarbonate films with well transparency and flexibility. These amino groups are easily converted to ammonium salts by protonation with acids, while the quaternization with benzyl bromide is strongly affected by the steric hindrance of these amines. N-Methyldiethanolamine or N, N-dimethylethanolamine residues in these films react easily with benzyl bromide to give quaternary ammonium salt-functionalized films. (C) 2015 Wiley Periodicals, Inc.

DOI： 10.1002/pola.27922

Language：English   Publishing type：Research paper (scientific journal)  

Synthesis and hydrolytic properties of water-soluble poly(carbonate-hydroxyurethane)s from trimethylolpropane
Water-soluble poly(carbonate-hydroxyurethane)s (PCHUs) comprising hydroxyurethane-carbonatehydroxyurethane repeating units with well-controlled molecular weight and polydispersity were synthesized from trimethylolpropane (TMP) and investigated for their hydrolytic properties in aqueous media at different pH values. The reaction of TMP with diphenyl carbonate affords mainly three types of different-structured TMP-based carbonates. By fine tuning the synthetic conditions, the bifunctional sixmembered cyclic carbonate bridged by an acyclic carbonate bond (TMPC1) was obtained in 36.8% yield after purification. The polyaddition of TMPC1 and 1.25 equiv. of 1,3-diaminopropane at -10 degrees C proceeds without the cleavage of the acyclic carbonate linkages to form PCHUs comprising four repeating units with amino terminals. Furthermore, the reaction of their amino terminals with a, alpha,alpha'-diisothiocyante-p-xylene forms thiourea linkages (-NH-C(=S)-NH-) to extend the chain length of the PCHUs without the inter/intra chain cross-linking via their hydroxyl side chains. After carboxylation of the hydroxyl side chains of the PCHUs with succinic anhydride and neutralization with sodium bicarbonate, water-soluble PCHUs can be obtained. The urethane bonds of the PCHUs are stable, while carbonate and ester bonds are gradually hydrolyzed in alkaline aqueous media at ambient temperature. In particular, the water-soluble PCHUs are completely decomposed to their basic structures in carbonate buffers at pH 10.6 within one week.

DOI： 10.1039/c5py01733e

Language：English   Publishing type：Research paper (scientific journal)  

Polyhydroxyurethanes (PHUs) are synthesized by the polyaddition of di(trimethylolpropane) carbonate (DTMPC) and a series of conventional aliphatic diamines, and are then chemically modified through their side chains to design quaternary ammonium chloride (QAC)-functionalized PHU films. The reaction of DTMPC with a subtle excess of diamines affords PHUs with well-controlled molecular weights and polydispersities. The hydroxyl groups of these PHUs are modified with chloroacetyl chloride and then reacted with N,N-dimethyl-n-octylamine (DMOA) to easily give QAC-functionalized PHUs. On the other hand, the reaction of these PHUs with cross-linkable N,N,N',N'-tetramethyl-1,6-diaminohexane (TMDAH) undergoes quaternization and simultaneously forms networked structures, resulting in the formation of QAC-functionalized PHU network films. In particular, the use of 20 mol% TMDAH, with respect to the chloroacetyl groups of the PHU unit, gives a self-supported film with a good transparency and higher thermal stability. Furthermore, the remaining chloroacetyl groups of the film can be modified with DMOA to afford PHU films with dual-structured QAC moieties. The resulting PHU film constructs positively charged surfaces with a zeta potential of +8.3 mV.

DOI： 10.1039/c5ra09885h

Language：English   Publishing type：Research paper (scientific journal)  

The synthesis of six-membered cyclic carbonates from diols utilizing less toxic and easily-handled diphenyl carbonate (DPC) is carried out based on the reactivity and selectivity at different conditions. Commercially-available neopentylglycol (NPG) or di(trimethylolproapane) (DTMP) react effectively with DPC at 140 degrees C and converted to their corresponding monofunctional NPG-carbonate (NPGC) or bifunctional DTMPC-carboante (DTMPC), respectively. The selectivity of these carbonates changes depending on a feed ratio of DPC and these diols. After a NPG/DPC mixture with the DPC/NPG feed ratio of 4 was heated at 140 degrees C for 48 h, the NPGC is isolated with a yield of 74%. A 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed ring-opening polymerization (ROP) of NPGC with DTMPC can form effectively networked structures. By only drying of THF solutions containing NPGC, DTMPC, and a catalytic amount of DBU at 60 degrees C for 12 h, the ROP efficiently proceeds and networked polycarbonate films with well transparency and flexibility are easily obtained. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41956.

DOI： 10.1002/app.41956

Language：English   Publishing type：Research paper (scientific journal)  

D-Glucaric acid (D-Glc) associates with linear poly(ethyleneimine) (PEI) through hydrogen bonding and electrostatic interactions in aqueous media to form nanostructured crystalline PEI/D-Glc/H2O complexes with PEI/D-Glc/H2O ratios of 2:1:2. These complexes can serve as templates for silica depositions from hydrolytic condensation of tetramethoxysilane to guide morphologically duplicated silica under very mild conditions. Their microscale morphologies are tunable by use of the crystalline complexes regulated in the different pH of the PEI/D-Glc solutions. It was also found that some metal ions added in the PEI/D-Glc complexation process could have a synergistic effect under a certain pH regimes, bringing about remarkable changes in the hierarchy of the resulting complexes. Especially, the complexes formed through fine-tuning of the complexation conditions could direct torsionally stacked silica nanosheets, in which the nanosheets are composed of orderly-bundled nanofibrils. Final elimination of organic components of the templates afforded chiral inorganic silica while retaining the morphologically higher-order structures. The chirality of the silica, which was obtained after calcination at 600 degrees C, was characterized by means of diffused reflectance circular dichroism (DRCD) spectroscopy with a remote confirmation of the appearance of induced-CD (ICD) signals of achiral or racemic chromophores covalently linked on the silica frames. Interestingly, the shapes and signs of these ICD signals are dramatically changed depending on the pH-tuned templates used in silicification and are strongly correlated to that of the CD signals of the complex templates, indicating that the chiral transcription proceeds accurately with imprinting the higher-order chirality of the complexes on the morphologically structured silica networks.

DOI： 10.1002/chem.201303343

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/anie.201108914

Language：English   Publishing type：Research paper (scientific journal)  

The formation of silica films on the glass plate whose surface was precoated by crystalline linear poly(ethylenimine) (LPEI) in advance was systematically investigated via controlling the surface-specific crystallization of the LPEI on the glass plate. Immersing glass substrates into a hot aqueous solution of LPEI containing additives such as transition metal ions and acidic compounds and retaining them on 30 degrees C for desired periods resulted in the formation of crystalline LPEI layers on the substrates. Subsequently dipping this LPEI-coated glass into silica source solutions afforded successfully hierarchically structured silica film which coated continuously the surface of the substrates. In this two-step process, we found that the formation of hierarchically structured silica films strongly depended on the LPEI layer formed from the LPEI aqueous solutions containing different additives. The LPEI layer formed by changing the kinds of additives and their concentrations provides the differently structured silica films composed of turbine-like structures flatly lying-on and/or vertically standing-on as well as ribbon network structures on the surface of the substrates. Moreover, we functionalized these silica films by the introduction of hydrophobic alkyl chains or emissive Eu(III) complexes and investigated their wettability and emission properties.

DOI： 10.1021/la2004547

Language：English   Publishing type：Research paper (scientific journal)  

Linear poly(ethyleneimine) (LPEI) is easily crystallizable with the formation of various morphologies in the aqueous medium when its hot solution cooled down to room temperature. Herein, we prepared a series of crystalline precipitates of LPEI grown in the presence of proton donating compounds such as Tris-HCl, tartaric acid, amino acids, and used the precipitates in directing silica deposition. Since the proton donating compounds can mediate the pH with donating the proton to LPEI, the crystallization of LPEI evidently depended on the concentrations of the proton donating compounds. It was found that the precipitates grown in the conditions of the pH ranged 8.2-8.5 directed well-controlled bent nanosheet of silica/LPEI composites. The bent nanosheet is constructed by multi-layered structures with a little slippage between layers. The bent nanosheet silica has slit-like pore with ca. 10 nm width.

DOI： 10.1007/s11051-010-0065-5

Language：English   Publishing type：Research paper (scientific journal)  

The formation of hierarchical aggregates from linear polyethyleneimine (LPEI) was performed in aqueous media containing a series of divalent metal ions (Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)) and their organization processes are investigated by transcribing the structure into hard silica frames which can be appropriately characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurements. Coexisting metal salts interact with LPEI via coordination bonds between metal ions and amine groups in ethyleneimine (EI) units to form water-soluble complexes. Without suitable complexation, LPEI crystallizes without restriction and forms non-well controlled hierarchical microstructures even in the presence of metal ions. The molar ratios of EI units and metal ions strongly affect the morphologies of crystalline precipitates. Low values of the ratios lead to intricate flower-like structures composed of leaf-like fibers assembled in a random fashion. On the other hand, an increase of the ratios makes the structures well-shaped and flattened for constructing 2-D turbine-like morphology. These structures consist of numerous sheet structures grown in a radial fashion. XRD and XRF measurements reveal that these resulting solids are mainly composed of hydrated LPEI and imply that coordinating metal ions are located in the peripherals of LPEI microstructures. Finally, temporal morphological evolution experiments indicate that a metal ion which can coordinate with EI units serves as a regulator in the crystallization of LPEI and abundant crystal growth can proceed.

DOI： 10.1039/b909023c

Language：English   Publishing type：Research paper (scientific journal)  

Linear Fe(II)1,2,4-triazole complexes with lipid counteranions are newly developed. These complexes show sharp and reversible spin conversion in toluene, with temperatures significantly higher (by 20-100 K) than the spin crossover temperatures observed in the crystalline states. This is accounted for in terms of increased metal-ligand interactions in organic media, which is caused by solvophobic compaction of charged coordination chains. In atomic force microscopy, developed nanowires are observed for low spin (I-S) complexes. On the other hand, fragmented nanostructures are seen for high spin (HS) complexes, indicating that the spin conversion in solution is governed by a self-assembly process. The lipid packaging of charged coordination chains thus provides powerful means to improve and regulate their functions via solvophobic self-assembly.

DOI： 10.1021/ja711355j

Language：English   Publishing type：Research paper (scientific journal)  

Lipophilic, linear iron(II) 1,2,4-triazole complexes with 9,10-dimethoxyanthracene-2-sulfonate and 1-pyrenesulfonate counter ions are newly developed. These complexes are dispersed in toluene as nanofibers and display dynamic spin conversion characteristics. Photorelaxation process of 1-pyrenesulfonate accumulated on the complex is regulated depending on the spin state of iron(II) triazole complexes.

DOI： 10.1246/cl.2008.446

Language：Others   Publishing type：Research paper (other academic)  

A novel family of lipophilic, photo-responsible supramolecular wires that contain 1D Fe(II) triazole complexes is developed. A triazole ligand 2 contains azobenzene group and it formed a 1D iron(II) complex Fe(2)3(BF 4)2, which is soluble in common organic solvents. Atomic force microscopy (AFM) of the sample in dilute chloroform solutions showed flexible molecular wires (length, 10 - 100 nm, width, ca. 7 nm). On the other hand, it formed aggregates and gave organogels when dispersed in chlorocyclohexane. The yellow chlorocyclohexane gel is liquefied by UV-irradiation and an orange-colored solution was obtained. This is ascribed to the trans-to-cis photoisomerization of azobenzene units, which is accompanied by morphological changes to undulated molecular wires. Visible-light illumination of the Fe(cw-2)3(BF4)2 complex reversibly afforded Fe(trans-2)3(BF4)2 complex, which is accompanied by physical gelation. Thus, the molecular wire of Fe(2) 3(BF4)2 show reversible conformational changes with maintaining the linear complex structures. This is the first example of photo-responsive 1D metal complexes which are dispersed in solution.

Language：Others  

Language：Others