Carbon Dioxide‐Controlled Assembly of Water‐Soluble Conjugated Polymers Catalyzed by Carbonic Anhydrase

The CO₂‐responsive and biocatalytic assembly based on conjugated polymers has been demonstrated by combining the signal amplification property of the polythiophene derivative (PTP) and the catalytic actions of carbonic anhydrase (CA). CO₂ is applied as a new trigger mode to construct the smart assembly by controlling the electrostatic and hydrophobic interactions between the PTP molecules in aqueous solution, leading to the visible fluorescence changes. Importantly, the assembly transformation of PTP can be specifically and highly accelerated by CA based on the efficient catalytic activity of CA for the inter‐conversion between CO₂ and HCO₃⁻, mimicking the CO₂‐associated biological processes that occurred naturally in living organisms. Moreover, the PTP‐based assembly can be applied for biomimetic CO₂ sequestration with fluorescence monitoring in the presence of CA and calcium.

     

Water‐soluble conjugated polymers: Synthesis and optical properties

Two sets of water‐soluble poly(phenylene vinylene)s were synthesized and their optical properties were studied. The aqueous solubility of all these polymers is rendered by pendant sulfonate groups. One set of polymers (polymer I series) contains, in addition to the sulfonate pendants, dimethoxy substituents, while the other (polymer II series) contains oligo(ethylene oxide) side chains. Within each set, polymers containing lithium (Ia and IIa), sodium (Ib and IIb), and potassium (Ic and IIc) counter ions were prepared. The two sets of polymers showed different properties from physical appearance (fiber vs film) to thermal properties and to optical properties. It was found that set I polymers, with shorter side chains, exhibit stronger aggregation in aqueous solutions than set II polymers, which led to their lower fluorescence quantum yields and lower polymer‐to‐MV²⁺ quenching efficiencies. Within each set, the effect of counter ions on optical properties was noted. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5123–5135, 2007     

Synthesis and Characterization of Uncharged Water‐Soluble Star Polymers Containing a Porphyrin Core

Uncharged water‐soluble porphyrins were prepared by reaction between tetrakis(p‐hydroxyphenyl)porphyrin and chlorinated poly(ethylene glycol) methyl ethers of different molecular weights. Water‐solubility was achieved by binding four poly(ethylene glycol) branches to a porphyrin core to give star polymers with molecular weights in the range 2000–21 000 Da. Structural characterization of these star polymers was performed by means of gel permeation chromatography, NMR spectroscopy, and MALDI‐TOF analysis.     

Anisotropic Electronic Conductivity in Layer‐By‐Layer Composite Film Composed of Water‐Soluble Conjugated Polymers and SWNTs

This paper reports the anisotropic electrical properties of a layer‐by‐layer (LBL) film composed of water‐soluble conjugated polymers and single‐walled carbon nanotubes (SWNTs). The water‐soluble poly (p‐phenylene ethynylene)s (PPEs) are capable of a strong π‐π interaction with the sidewall of SWNTs and results in a very stable PPE‐SO₃/SWNTs composite in aqueous solution. Aligned LBL films were prepared by self‐assembly using the anionic PPE/SWNTs and cationic PPE on various substrates. The polarized Raman spectra exhibited the cos²α polarization dependence of the G‐band intensity between the polarization direction and the SWNTs alignment direction. The electric conductivity within the LBL films can be controlled by the deposition direction in the LBL formation.

     

A Water‐Soluble Polycarbonate With Dimethylamino Pendant Groups Prepared by Enzyme‐Catalyzed Ring‐Opening Polymerization

A water‐soluble polycarbonate with dimethylamino pendant groups, poly(2‐dimethylaminotrimethylene carbonate) (PDMATC), is synthesized and characterized. First, the six‐membered carbonate monomer, 2‐dimethylaminotrimethylene carbonate (DMATC), is prepared via the cyclization reaction of 2‐(dimethylamino)propane‐1,3‐diol with triphosgene in the presence of triethylamine. Although the attempted ring‐opening polymerization (ROP) of DMATC with Sn(Oct)₂ as a catalyst fails, the ROP of DMATC is successfully carried out with Novozym‐435 as a catalyst to give water‐soluble aliphatic polycarbonate PDMATC with low cytotoxicity and good degradability.     

Water‐Soluble Metallocene‐Containing Polymers

Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox‐activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water‐soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water‐soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene‐ and ruthenocene‐containing and charged cobaltocenium‐containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self‐assembly behavior, and other benefits of the obtained materials are discussed.

     

Large‐Scale Synthesis of Water Soluble Non‐Ionic Dendrons by Stepwise Extraction Purifications

First and second generation aliphatic polyether dendrons based upon poly(ethylene oxide) (PEO) peripheries have been prepared using a combination of a Williamson etherification and hydroboration/oxidation reactions. The purification after each synthetic step was performed by stepwise extraction, after which the reaction yields were found to be greater than 80%. The dendrons obtained showed narrow molecular weight distributions of less than 1.09, and this was confirmed by mass spectrometry and gel permeation chromatography. Since the synthesis procedure did not involve column chromatography, it was successfully scaled up to larger quantities. The hydrophilic non‐ionic dendrons prepared by this straightforward method may be employed as building blocks in the design of functional soft materials such as ionic conductors and drug carriers.

     

Water‐Soluble N‐(n‐Fatty acyl)chitosans

Chitosan was partially N‐acylated by treatment with n‐fatty acid anhydrides in a homogeneous solution in 2 vol.‐% aqueous acetic acid‐methanol (1:2 v/v). The degree of substitution (d.s.) for N‐acyl groups in the water‐soluble N‐acylchitosan derivatives was in the range of 0.42–0.82 for N‐acetyl, 0.37–0.76 for N‐propionyl, 0.52–0.71 for N‐butyryl and 0.54–0.64 for N‐pentanoyl and ca. 0.58 for N‐hexanoyl, respectively.

Water soluble N‐(n‐fatty acyl)chitosans.     

Thermoresponsive Synergistic Hydrogen Bonding Switched by Several Guest Units in a Water‐Soluble Polymer

Thermoresponsive synergistic hydrogen bonding (H‐bonding) switched by several guest units in a water‐soluble polymer is reported. Adjusting the distribution of guest units can effectively change the synergistic H‐bonding inside polymer chains, thus widely switch the preorganization and thermoresponsive behavior of a water‐soluble polymer. The synergistic H‐bonding is also evidenced by converting less polar aldehyde groups into water‐soluble oxime groups, which bring about the lowering‐down of cloud point and an amplified hysteresis effect. This is a general approach toward the wide tunability of thermosensitivity of a water‐soluble polymer simply by adjusting the distribution of several guest H‐bonding units.     

Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes

Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N‐heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high‐resolution TEM, and spectroscopic techniques. Solid‐state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a ¹³C–¹⁹⁵Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle.     

Metallo‐Supramolecular Diethylene Glycol: Water‐Soluble Reversible Polymers

Bis(2,2′:6′,2″‐terpyrid‐4′‐yl) diethylene glycol was synthesized as a monomer unit and further utilized for polymerization with FeCl₂ in order to form water‐soluble coordination polymers. Viscosity measurements and film‐forming properties indicate the formation of linear coordination polymers or larger ring structures. The terpyridine/iron(II) complexes are stable up to temperatures of 210 °C, but can be uncomplexed by the addition of an excess of a strong competitive ligand (HEDTA) under mild conditions.

     

A Water‐Soluble π‐Conjugated Polymer with up to 100 mg · mL−1 Solubility

A cationic water‐soluble polyfluorene (P2) containing a high density of tetraalkylammonium side chains in polymer backbone was synthesized and characterized. The polymer shows excellent water solubility up to 100 mg · mL⁻¹ as well as high photoluminescence (PL) quantum yield of 44% in water. The relatively high cationic density and appropriate side chain length of the polymer are the key factors to achieve such high water solubility. The reduction potential of P2 is decreased as compared with its neutral polymer, reflecting the enhanced electron injection abilities. The standard NPB/Alq₃ device using such a polymer as the electron injection layer shows nearly three‐fold enhancement in the electroluminescence (EL) efficiency.

     

Uncharged Water‐Soluble Metal‐Bis‐Porphyrins Like Molecular Tweezers for Amino Acids

Some new water‐soluble bis‐porphyrins, constituted of two porphyrin units spaced by means of aliphatic bridges of different lengths, were synthesized and characterized by MALDI‐TOF mass spectrometry, ¹H NMR and UV‐vis spectroscopy. The hydrosolubility of these uncharged compounds was guaranteed from the presence of six long PEG chains bound on the peripheral positions of the two porphyrins. Cobalt and zinc derivatives were also prepared. In the case of Co‐bis‐porphyrin, the appearance of induced circular dichroism (ICD) signals in water solution confirmed the formation of stable complexes with some amino acids, in which the bis‐porphyrin behaves like molecular tweezers.

     

Simple Silole‐Containing Polyfluorene for White Electroluminescence with Simultaneous Blue,Green, and Red Emission

Novel conjugated silole‐containing polyfluorenes, with green‐ and red‐emissive siloles on the backbone of the blue‐emissive polyfluorene are synthesized for white light electroluminescence (EL) from a single polymer with simultaneous red, green, and blue (RGB) emission. The CIE coordinates (0.33, 0.36) of the white light EL spectra are very close to that for pure white light (0.33, 0.33). The EL spectra are also quite stable at different applied voltages or brightness. The relative intensities for the three RGB peaks, at 450, 505, and 574 nm, were 0.94, 1, and 0.97, respectively, which demonstrates a balanced simultaneous RGB emission. A maximum luminous efficiency of 2.03 cd · A⁻¹ for a brightness of 344 cd · m⁻², and a luminous efficiency of 1.86 cd · A⁻¹ for a more practical brightness of 2 703 cd · m⁻², were achieved.

     

Ionic‐Liquid‐Derived,Water‐Soluble Ionic Cellulose

A new type of water‐soluble ionic cellulose was obtained by means of the dissolution of cellulose in dimethylimidazolium methylphosphite at elevated temperatures over 120 °C. FTIR spectroscopy, ¹H and ¹³C NMR spectroscopy, and elemental analysis results revealed that the repeating unit of the water‐soluble cellulose consists of a dialkylimidazolium cation and a phosphite anion bonded to cellulose. The degree of phosphorylation on the cellulose chain was between 0.4 and 1.3 depending on the reaction temperature and time. With an increasing degree of phosphorylation, water solubility was increased. Scanning electron microscopy and X‐ray diffraction analyses revealed that the cellulose crystalline phase in the parent crystalline cellulose changed to an amorphous phase upon transformation into ionic cellulose. Thermogravimetric analysis showed the prepared phosphorylated cellulose was stable over 250 °C and a substantial amount of residue remained at 500 °C.     

Water‐soluble anionic conjugated polymers for metal ion sensing: Effect of interchain aggregation

Three sulfonato‐containing fluorene‐based anionic water‐soluble conjugated polymers, which are specially designed to link fluorene with alternating moieties such as bipyridine ( P1 ), pyridine ( P2 ), and benzene ( P3 ) have been synthesized via the Pd‐catalyzed Sonogashira‐coupling reaction, respectively. These polymers had good solubility in water and showed different responses for transition metal ions with different valence in aqueous environments: the fluorescence of bipyridine‐containing P1 can be completely quenched by addition of all transition metal ions selected and showed a good selectivity for Ni²⁺; the pyridine‐containing P2 had a little response for monovalent and divalent metal ions while showed good quenching with the addition of trivalent metal ions (with a special selectivity for Fe³⁺); P3 had responses only for the trivalent metal ions within the ionic concentration we studied. After investigation of the UV‐vis absorption spectra, PL emission spectra, DLS, and fluorescence lifetime of P1 – P3 in aqueous solution when adding transition metal ions, we found that the different spectrum responses of these polymers are attributed to the different coordination ability of the units linked with fluorene in the main chain. The energy or electron‐transfer reactions were the main reason for fluorescence quenching of P1 and P2 . On the other hand, interchain aggregation caused by trivalent metal ions lead to fluorescence quenching for P3 and also caused partly fluorescence quenching of P1 and P2 . These results revealed the origin of ionochromic effects of these polymers and suggested the potential application for these polymers as novel chemosensors with higher sensing sensitivity in aqueous environments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5057–5067, 2009     

Fluorescence‐Amplifying Assay for Irradiated DNA Lesions Using Water‐Soluble Conjugated Polymers

A new platform has been developed for DNA lesion detection using a cationic conjugated polymer (CCP). DNA that contains two adjacent thymine bases is irradiated with ultraviolet light to allow for the formation of cyclobutane pyrimidine dimers and pyrimidine–pyrimidone dimers. The DNA lesions block the primer extension, and the base labeled with fluorescein cannot be incorporated into the DNA strand. Addition of the CCP leads to inefficient fluorescence resonance energy transfer (FRET) from CCP to fluorescein. For the case without DNA lesions, successful primer extension allows for efficient FRET between them. In view of the FRET signal changes, the DNA lesions can be detected. This new protocol offers a convenient detection for DNA lesions in aqueous solution without any isolation and washing steps.

     

Interpolymer Complexes of Water‐Soluble Nonionic Polysaccharides with Polycarboxylic Acids and Their Applications

Literature data as well as our own experimental results devoted to the complexation of polycarboxylic acids with various water‐soluble polysaccharides (methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, starch, and dextran) by means of hydrogen bonding are systematized and analyzed. The specific peculiarities of interpolymer complexes based on polysaccharides‐polycarboxylic acids are demonstrated. The perspectives for the application of these interpolymer complexes are considered. It was shown that these materials possess good biocompatibility and adhesive properties. The promising directions for further study of interpolymer complexes between polycarboxylic acids and nonionic polysaccharides as well as existing gaps in the knowledge in this field are pointed out.

Formation of compact IPCs and hydrophilic interpolymer associates.