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Organic synthesis without an organic solvent is still the exception. In this microreview, we discuss and compare different synthetic methods that proceed in the absence of conventional organic solvents. This includes solvent‐free methods in solids (mechanochemistry and solid‐state photochemistry), and in neat liquids (thermal and photocatalytic), as well as the application of unconventional solvents, such as ionic liquids and deep‐eutectic solvents. The different approaches are briefly introduced and examples illustrate their specific advantages, followed by a critical discussion of their limitations. Some methods have the intrinsic benefits of solvent‐free operation, such as avoiding solubility problems and side‐reactions with the solvent. However, every method has specific advantages and the demand of the synthetic application is crucial for selecting the best technique. [ABSTRACT FROM AUTHOR]

A simple one-pot procedure is described for the synthesis and purification of 4'-substituted 4,4''-di-tert-butyl-2,2':6',2''-terpyridine ligands. The new series of ligand display improved solubility in most organic solvents in comparison to traditional 2,2':6',2''-terpyridine ligands. [ABSTRACT FROM AUTHOR]

Novel phosphorous triazatetrabenzocorrole (4) bearing non-peripheral octatrifluorobutoxy groups was successfully synthesized, with an aim to develop potential far-red sensitizer for dye sensitized solar cells. The dye was characterized by ¹H NMR, IR, mass, and UV-vis spectral techniques. It showed excellent solubility in majority of common organic solvents. Aggregation behavior of the dye 4 was investigated in several solvents with increasing dielectric constants. This dye-4 was found to be adsorbed on the nanoporous TiO2 via axial ligation. Further implication of structure of dye due to incorporation of CF3 group on the energy levels was evaluated by theoretical and experimental approaches. The intense far-red absorption of dye 4 including its excellent solubility and proper control of its energy levels makes it a promising candidate for its application as sensitizer in dye sensitized solar cells. [ABSTRACT FROM AUTHOR]

Traditional organic chemistry, and organic synthesis in particular, relies heavily on organic solvents, as most reactions involve organic substrates and catalysts that tend to be water-insoluble. Unfortunately, organic solvents make up most of the organic waste created by the chemical enterprise, whether from academic, industrial, or governmental labs. One alternative to organic solvents follows the lead of Nature: water. To circumvent the solubility issues, newly engineered "designer" surfactants offer an opportunity to efficiently enable many of the commonly used transition metal-catalyzed and related reactions in organic synthesis to be run in water, and usually at ambient temperatures. This review focuses on recent progress in this area, where such amphiphiles spontaneously self-aggregate in water. The resulting micellar arrays serve as nanoreactors, obviating organic solvents as the reaction medium, while maximizing environmental benefits. [ABSTRACT FROM AUTHOR]

Abstract: New platinum(II) complexes containing aminophosphonate ester were synthesized and fully characterized, which were found to possess better solubility in both organic solvents and water than cisplatin. These platinum(II) complexes exhibited considerable cytotoxicity against tumor cells MG-63, SK-OV-3, HepG2, BEL-7404 and low cytotoxicity to normal human liver cells HL-7702. Their antitumor activities were achieved through the induction of cell apoptosis and the cell cycle arrest at G1 phase. The electrophoretic mobility studies and CD spectral analysis revealed that the binding mode of complex 6 to DNA might be different from that of cisplatin. [Copyright &y& Elsevier]

A novel fluorinated pyridine-containing aromatic diamine monomer, 4-phenyl-2,6-bis[2-(4-amino-2-trifluoromethyphenoxy)phenyl]pyridine (o, p-6FPAPP), was prepared in a three-step synthetic route. This aromatic diamine was then employed to synthesize a series of fluorinated pyridine-containing polyimides (PIs) by polycondensation with various aromatic dianhydrides via the conventional two-step method. The inherent viscosities of the resulting poly(amic acid)s (PAAs) and PIs were in the range of 0.71–0.89 and 0.62–0.84 dL/g; all the PIs obtained by chemical imidization were readily soluble in common organic solvents such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and so on. Meanwhile, transparent, strong and flexible PI films were obtained, which had good thermal stability, with the glass transition temperature (Tg) of 195.2°C–232.7°C, the temperature at 10% weight loss of 530.2°C–546.0°C in nitrogen atmosphere, and good optical transparency with the cutoff wavelengths of 354–382 nm, as well as outstanding mechanical properties with tensile strengths of 96.4–105.8 MPa, tensile modulus of 1.57–1.88 GPa and elongations at break of 9.5%–13.4%. The PI films were also found to possess low water uptake of 0.52%–0.67%. [ABSTRACT FROM PUBLISHER]

Abstract: Two novel spirobifluorene-cored dendrimers containing polyphenylene dendrons with the carbazole (spiro-Cz) and cyano surface groups (spiro-CN) were synthesized and characterized. Both the dendrimers show good solubility in common organic solvents. Spiro-Cz is amorphous even when it is obtained directly from organic solvents and an extremely high glass transition temperature of 332 °C is detected. These dendrimers can be reversibly oxidized and reduced in electrochemical measurements. They are blue fluorescent with small red-shift in solid film absorption and fluorescence spectra. These advantageous merits are suggested to benefit from the combined contribution from the spirobifluorene core and the bulky polyphenylene dendrons. They were used as emitting layer to fabricate organic light-emitting diodes (OLEDs). Deep-blue electroluminescence was obtained for both dendrimers devices. [Copyright &y& Elsevier]

In this study, a new cation-exchange coating for stir bar sorptive extraction (SBSE) based on poly (acrylic acid-ethylene dimethacrylate) monolithic material was synthesized. The effect of polymerization conditions such as the ratio of functional monomer to cross-linker and the content of porogenic solvent on the extraction efficiencies were investigated in detail. The monolithic material was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to evaluate the usability of the new coating for the extraction of inorganic cations, the analysis of soluble K+, Mg2+and Ca2+in milk by ion chromatography with conductivity detection was selected as a paradigm. Several extractive parameters, including pH value in sample matrix, desorption solvent, extraction and desorption time were optimized. Under the optimum conditions, low detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target cations were achieved within the range of 0.12–0.28 and 0.4–0.92 μg L−1, respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction of inorganic cations. Finally, the proposed method was successfully used to analyse three different trademarks of commercial milk samples with satisfactory recoveries in the range of 71.1% to 102.8%. [ABSTRACT FROM AUTHOR]

Abstract: The novel optically active Pc-4 (neutral) and Pc-5 (ionic), zinc(II) phthalocyanines having four N-benzyl protected l-prolinol unit were synthesized. l-prolinol has binucleophilic character and can be anchored to phthalonitrile derivative from both nitrogen and oxygen atoms. In order to overcome this problem and to enhance the solubility of phthalonitrile (S)-(-)-3 and the target phthalocyanines, the nitrogen atom of l-prolinol was first protected with benzyl chloride. All the compounds were characterized by 1H and 13C NMR, MALDI–TOF MS, IR, UV–vis, and Circular Dichroism (CD) spectroscopy. Pc-4 is highly soluble in most common organic solvents, whereas ionic Pc-5 is soluble in water. The CD results showed that the chiral information was transferred from the peripheral chiral l-prolinol side chains to the phthalocyanine chromophore at the molecular level. [Copyright &y& Elsevier]

Abstract: Three stable polyradicals with large π-conjugated planar phenalenyl (PLY) radical units as side chain were synthesized. Due to the different conjugated backbones and the interactions between main chains and side chains, these polyradicals and their corresponding precursor polymers presented diverse optical and electrical properties, which were confirmed by UV–vis, fluorescence and CV detections. Besides, they showed excellent solubility in common organic solvents and good stability in the air. Considering their special characteristics, we have fabricated photovoltaic (PV) devices using these polyradicals or polymers as donor material and PCBM as acceptor material. The significant PV performance improvement was observed using a radical-based active layer in the PV devices. [Copyright &y& Elsevier]

Abstract: A series of novel polyamides that carry carbazole-containing pendent was prepared by direct polycondensation of a diamine, N-(4-(carbazol-9-yl)phenyl)-3,5-diaminobenzamidamide (DAC), and various aliphatic and aromatic dicarboxylic acids. All the resulting polyamides were amorphous with inherent viscosities ranged from 0.51 to 0.65dL/g and were readily soluble in many organic solvents which could be solution-cast into transparent and tough films. The glass transition temperatures (Tg ) of these polymers were affected considerably by their chemical structure and ranged from 195 to 300°C. They had useful levels of thermal stability associated with relatively high temperatures of 10% weight loss (T 10) in the range of 385–480°C in nitrogen atmosphere. These polymers exhibited strong UV–vis absorption maxima in solution and in solid state, and their photo- and chemi-luminescence properties were studied. photoluminescence (PL) efficiency of the polyamides were affected by their chemical structure (PL quantum yield up to 32%). The aliphatic polyamides emitted blue light (λ e.max =435–450nm), while the aromatic polyamides emitted green light (λ e.max =485–492nm) both in solution and solid state. [Copyright &y& Elsevier]

Abstract: Poor solubility of carbon nanotubes (CNTs) in water and organic solvents offers a significant problem for their applications. Macromolecules can be suitable solubilizing agents and a structural component of composite materials for CNTs. Several polymers were tested for the preparation of CNT dispersions. In this study, a poly[(4-pyridineoxy)(phenoxy)phosphazene] (3) was prepared by sequential treatment of poly(dichlorophosphazene) (2) with sodium 4-pyridineoxy and sodium phenoxide in THF. Multi-walled carbon nanotube/poly(organophosphazene) composites (f-MWCNT/PZS) with different feed ratios [R feed = 1:1, 1:3, 1:5 and 1:10 (w/w)] were obtained by the treatment of the functionalized multi-walled carbon nanotube (f-MWCNT) with the protonated poly(organophosphazene) (PZS). Excellent dispersions of the f-MWCNT/PZS nanocomposites in water and common organic solvents were achieved. The influence of feed ratio on polymer coating and the stability of composites were investigated by thermal gravimetric analysis (TGA). f-MWCNT/PZS1:5 nanocomposite was characterized by 31P, 1H NMR, FTIR, XRD, EDX and Raman Spectroscopy. The morphologic characterizations of f-MWCNT/PZS1:5 were carried out by HRTEM and SEM methods. [Copyright &y& Elsevier]

Abstract: Sulfonated polybenzothiazoles with benzimidazole moieties were successfully prepared by polycondensation. For comparison purpose, sulfonated polybenzothiazoles were also synthesized. Rigid-rod sulfonated polybenzothiazoles generally show poor solubility in organic solvents, whereas these sulfonated polybenzothiazoles with high sulfonation degree are soluble, but the membranes cast from them swell excessively in water. Thus they could not be used as proton exchange membranes (PEMs). The comparison study demonstrates that the incorporation of benzimidazole moieties to sulfonated polybenzothiazoles greatly enhances the solubility of products. The resulting copolymers thus could be cast into the membranes as PEMs. The benzimidazole moieties in the resulting polymers improve thermal properties, dimensional stability, tensile strength, Young''s modulus, and oxidative stability, but they decrease proton conductivity and the elongation at break, due to the ionic cross-linking and hydrogen bonds. Even so, sulfonated polybenzothiazoles with appropriate content of benzimidazole moieties (10mol%) could still display a high proton conductivity of 0.094Scm−1 at 80°C and an elongation at break of 26.1%. These ionomers exhibited excellent overall properties such as excellent mechanical properties, high thermal and oxidative stability, low swelling, and high proton conductivity, thus they might be a candidate for proton exchange membranes. [Copyright &y& Elsevier]

Abstract: Two low bandgap conjugated polymers containing vinylene unit on their main chains, poly(dithienosilole vinylene) derivatives P1 and P2, were synthesized by Pd-catalyzed Stille-coupling method. The two polymers show good solubility in common organic solvents, broad absorption bands from 500nm to 700nm and lower energy bandgap of 1.72eV for P1 and 1.77eV for P2. The electronic energy levels of the polymers were measured by electrochemical cyclic voltammetry. The HOMO and LUMO energy levels of P1 and P2 are at −5.03eV, −5.18eV and −3.39eV, −3.43eV, respectively. The polymers P1 and P2 containing dithienosilole units show lower HOMO and LUMO energy levels, in comparison with other poly(thienylene vinylene) derivatives. [Copyright &y& Elsevier]

Abstract: A series of five symmetrical and four unsymmetrical diaryl substituted diketo-pyrrolo-pyrroles was synthesized; two unsymmetrical derivatives are reported for the first time. The relationship between the theoretical excitation energies of the S0 → S1 transition, computed by time dependent density functional theory and the experimental positions of 0–0 vibronic bands in the visible absorption (or fluorescence excitation) spectra was studied. Experimental data were obtained from either solution or from low temperature organic solvent glass, in which the progressions of the vibrational structure enabled correct assignment of vibronic sub-bands in some cases. Theoretical calculations predicted that a linear bathochromic and hyperchromic shift would accompany substitution of each phenyl in the parent 3,6-diphenyl-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione by providing a more extensively conjugated aryl centre (2-naphthyl, biphenyl, stilbenyl) for the ensuing planar derivatives. Qualitatively, the experimental bathochromic shifts of the 0–0 vibronic sub-bands were in exact agreement with theory, whilst hyperchromic shifts were affected by the very low solubility of the planar, symmetrical derivatives. Deviations from this ideal behaviour were observed for non-planar derivatives (aryl = stilbenyl or 1-naphthyl), for which the dihedral angles describing the aryl, out-of-plane torsions were probably underestimated by DFT. [Copyright &y& Elsevier]

Styrenic dendrons functionalized with ferrocenyl and chloromethylsilyl termini were synthesized and polymerized by the AIBN-initiated radical polymerization procedure yielding a ferrocenyl dendronized polymer and a chloromethylsilyl dendronized polymer, respectively. The latter polymer was functionalized with ferrocenyl groups using “click” chemistry. The ferrocenyl dendronized polymers are soluble in common organic solvents such as tetrahydrofuran, dichloromethane, and chloroform. They show a reversible ferrocenyl wave in cyclic voltammetry (CV) and form derivatized Pt electrodes. Their sizes and shapes were examined by size exclusion chromatography (SEC), atomic force microscopy (AFM), dynamic light scattering (DLS) and DOSY 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel fluorinated poly(aryl ether)s containing phthalazinone moieties (FPPEs) have been prepared by a modified synthetic procedure for optical waveguide applications. The obtained random copolymers exhibited excellent solubility in polar organic solvents, high glass transition temperatures (T gs: 185–269°C), good thermal stabilities (the temperatures of 1% weight loss: 487–510°C) and good optical properties. By adjusting the feed ratio of the reactants, the refractive indices of TE and TM modes (at 1550nm) could be well controlled in the range of 1.575–1.498 and 1.552–1.484, respectively. The optical losses of the FPPEs exhibited relatively low values (less than 0.27dB/cm at 1310nm). Additionally, the thermo-optic coefficient (dn/dT) values of the FPPEs at 1310nm and 1550nm (TE mode) ranged from −0.97×10−4 °C to −1.33×10−4 °C and from −0.96×10−4 °C to −1.29×10−4 °C, respectively. [Copyright &y& Elsevier]

Abstract: The synthesis of novel, symmetrical, hexadecasubstituted phthalocyaninatozinc(II) bearing eight, fluorinated phenoxy groups in peripheral positions and eight, non-peripheral hexyloxy groups as well as their related unsymmetrical derivatives is described. The compounds were characterized by 1H NMR, GC–MS, UV–vis and IR. The synthesized ZnPc complexes possess excellent solubility in various organic solvents such as CH2Cl2, THF, acetone and ethyl acetate and do not readily aggregate in solution. The new complexes show interesting luminescence properties in different organic solvents. [Copyright &y& Elsevier]

The reaction of 1-formyldipyrromethane (100 mM) in toluene at 115 °C containing DBU (10 mol equiv) and MgBr2 (3 mol equiv) in the presence of air affords the magnesium chelate Mg(II) porphine in 30-40% yield. The advantages of the new method include simplicity, high concentration, chromatography-free purification, gram-scale synthesis, and avoidance of the poorly soluble free base porphine. Mg(II) porphine exhibits good solubility in common organic solvents and is a valuable core scaffold for derivatization. [ABSTRACT FROM AUTHOR]

Glycosylation of 6-(substituted-imidazol-1-yl)purine sodium salts with 2-deoxy-3,5-di-O-(p-toluoyl)-α-D-erythro-pentofuranosyl chloride proceeds with regiospecific formation of the N9 isomers. Base substrates with lipophilic substituents on the C6-linked imidazole moiety are more soluble in organic solvents, and the solubility is further increased with binary solvent mixtures. Selective solvation also diminishes the extent of anomerization of the chlorosugar. Stirred reaction mixtures of the modified-purine sodium salts generated in a polar solvent and cooled solutions of the protected 2-deoxysugar chloride in a nonpolar solvent give 2′-deoxynucleoside derivatives with N9 regiochemistry and enhanced β/α configuration ratios. Application of the binary-solvent methodology with 2-chloro-6-(substituted-imidazol-1-yl)purine salts in cold acetonitrile and the chlorosugar in cold dichloromethane gives essentially quantitative yields of the N9 isomers of β-anomeric 2′-deoxynucleoside intermediates. Direct ammonolysis (NH3/MeOH) of such intermediates or benzylation of the imidazole ring followed by milder ammonolysis of the imidazolium salt gives high yields of the clinical anticancer drug cladribine (2-chloro-2′-deoxyadenosine). [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and chemical polymerization of a thiophene disubstituted with an alkylic and an ω-bromine functionalized oligomethylenic chain is described. The obtained polymer, namely the poly[3-hexyl-4-(6-bromohexyl)thiophene], is completely soluble in common organic solvents and its structural, thermal and chemical–physical properties are compared with those of a ‘conventional’ bromohexyl 3-substituted polythiophene. The new polymer may be considered as a key-intermediate for the synthesis of multifunctional soluble polythiophenes since its self-plastifying feature may permit the insertion on the polymeric side-chains, by simple post-polymerization functionalization reactions, of sterically demanding or strongly interacting functional groups, without final solubility being compromised. [Copyright &y& Elsevier]

2-Phenyl-1 H -indole is an important chemical intermediate in organic syntheses. The solubility of 2-phenyl-1 H -indole in fourteen pure organic solvents was measured using the gravimetric method from 289.05 to 338.55 K at normal pressure. The results show that the solubility of 2-phenyl-1 H -indole in all the solvents increases as temperature rising. The melting point and fusion enthalpy of 2-phenyl-1 H -indole were measured with differential scanning calorimeter. The experimental solubility data were correlated with four thermodynamic models, including modified Apelblat equation, λh equation, Wilson equation and NRTL equation. The best correlation results were found with modified Apelblat equation. The mixing thermodynamic functions (Gibbs free energy, enthalpy and entropy) were calculated based on the Wilson equation. The results showed that the entire mixing process is spontaneous. Unlabelled Image • Solubility of 2-phenylindole in fourteen pure solvents was determined. • Solubility was correlated by Apelblat, λh , Wilson and NRTL model. • Thermodynamic properties of mixing process were also discussed. [ABSTRACT FROM AUTHOR]

The solubility of ammonium thiocyanate in different solvents (acetone, water, methanol, ethanol, ethanol + water mixtures) was measured by a synthetic method at different temperatures and at atmospheric pressure. The laser monitoring observation technique was used to determine the disappearance of the solid phase in a solid + liquid mixture. The results of these measurements were correlated with the modified Apelblat equation. [ABSTRACT FROM AUTHOR]