Rhodium-catalyzed convenient synthesis of functionalized tetrahydronaphthalenes

Convenient as well as convergent synthesis of functionalized tetrahydronaphthalenes has been accomplished under mild reaction conditions by the cationic rhodium(I)/H₈-BINAP complex-catalyzed [2+2+2] cycloaddition of 1,7-octadiyne derivatives with functionalized monoynes. The effect of the diyne tether lengths was investigated, which revealed that 1,6-heptadiyne and 1,7-octadiyne exhibit higher reactivity than 1,8-nonadiyne. Mechanistic studies indicated that the present rhodium-catalyzed [2+2+2] cycloaddition proceeds through the rhodacyclopentadiene intermediate generated by oxidative coupling of a diyne with rhodium. On the other hand, in the reactions of diynes and dimethyl acetylenedicarboxylate, the rhodacyclopentadiene intermediate generated by oxidative coupling of a diyne and a monoyne with rhodium would also be involved.     

Time delay reduction in low power ultrashort pulse and pulse stream propagation with overlapping soliton pair

Propagation of temporal 50 femtosecond pulse and pulse stream, which is realized by substituting each input pulse with reduced-order overlapping soliton pair, is investigated through short standard single-mode fiber. For the pulse stream the initial inter-pulse delay is selected to be 227 fs and the pulses are to be perturbed to avoid collision with the neighboring pulses. This method reduces the pulse time delay and properly retains the amplitude despite tradeoff between these two. This is a significant improvement in the low power femtosecond pulse and pulse stream propagation.     

ZnO thin films deposition by spray pyrolysis: Influence of precursor solution properties

Zinc oxide (ZnO) thin films were deposited by spray pyrolysis technique using different precursors. Three starting solutions salts namely: zinc acetate, zinc chloride and zinc nitrate were used. The properties of these solutions and their influence upon ZnO films growth rate are investigated. The obtained results indicate that the dissociation energy of the starting solution plays an important role on films growth rate. A linear relationship between the solution dissociation energy and the growth rate activation energy was found. However, the surface tension of the used solution controls the droplet shape impact. Both solution surface tension and dissociation enthalpy alter the microstructure of the formed film. Films deposited with zinc acetate are characterized by a smooth surface, dense network and high transparency, while films deposited with zinc chloride have a better crystallinity and low optical transmittance.     

Living ring‐opening polymerization of cyclic carbonates by titanium bisphenolate complexes

2,2′‐Methylenebis(6‐tert‐butyl‐4‐methylphenolate) titaniumdichloride ( 1 a ) brought about the living polymerization of 1,3‐dioxepan‐2‐one (7CC) to give polymers with narrow molecular weight distributions. The molecular weight of the obtained polycarbonate could be controlled by changing the initial mole ratio of 7CC and 1 a . The polycarbonate thus formed has hydroxymethylene terminal units at both ends.     

ATP-Responsive Nanoparticles Covered with Biomolecular Machine “Chaperonin GroEL”

Herein, we report an ATP-responsive nanoparticle (^GroELNP) whose surface is fully covered with the biomolecular machine “chaperonin protein GroEL”. ^GroELNP was synthesized by DNA hybridization between a gold NP with DNA strands on its surface and GroEL carrying complementary DNA strands at its apical domains. The unique structure of ^GroELNP was visualized by transmission electron microscopy including under cryogenic conditions. The immobilized GroEL units retain their machine-like function and enable ^GroELNP to capture denatured green fluorescent protein and release it in response to ATP. Interestingly, the ATPase activity of ^GroELNP per GroEL was 4.8 and 4.0 times greater than those of precursor ^cysGroEL and its DNA-functionalized analogue, respectively. Finally, we confirmed that ^GroELNP could be iteratively extended to double-layered NP.     

The first example of the copolymerization of cyclic acid anhydrides with oxetane by bulky titanium bisphenolates

The copolymerization of oxetane with glutaric anhydride was found to proceed with bulky titanium bisphenolate ( 1 ) as the initiator. The ¹H NMR spectrum of the produced copolymer shows that the copolymer contains both alternating units and oxytrimethylene units in the polymer main chain. 1 was also effective for the copolymerization of oxetane with other cyclic acid anhydrides, affording the corresponding copolymers. With the titanium bisalkolate complex ( 4 ), a copolymer rich in alternating sequences was obtained.     

Novel catalyst system for the synthesis of poly(alkylene oxide) with controlled molecular weight

An organoaluminum compound with bulky phenoxide groups as a Lewis acid can accelerate much the living polymerization of alkylene oxide initiated with aluminum porphyrin by the coordinative activation of the monomer. This concept can be extented to the polymerization initiated with aluminum Schiff base and tetraazaannulene complexes.     

On phosphorus chemical shift anisotropy in metal (IV) phosphates and phosphonates: A 31P NMR experimental study

The phosphorus chemical shift anisotropies, ³¹PΔcs, and asymmetry parameters η were measured by the ³¹P{¹H} NMR experiments in static and low-frequency spinning samples of the zirconium phosphates and phosphonates and also in the mixed Zr (IV)/Sn (IV) phosphate/phosphonate material. The data obtained have shown a 111 connectivity in the HPO₄ and PO₃ groups, which does not change at modification and intercalation of the materials. The ³¹PΔcs values of the phosphonate groups (43–49 ppm) significantly surpass the values characterizing the HPO₄ groups (23–37 ppm). The ³¹P Δcs values obtained for the metal (IV) phosphates were discussed in terms of P-O distances. The ³¹P chemical shift anisotropy parameters can help at elucidation of local structures in phosphate and phosphonate materials.     

Controlled polymerization reaction with new catalyst: Design of metalloporphyrin-acid systems for monomer activation

Metalloporphyrin initiator coupled with an appropriate organometallic Lewis acid catalyst could make possible the first example of living anionic polymerization of oxetane. Lewis acid built-in metalloporphyrins were designed as a new highly active catalyst/initiator system. The concept of monomer activation by Lewis acid was extended to the use of appropriate protonic acid.