Molecular symmetry. IV. The coupled perturbed Hartree–Fock method

Symmetry methods employed in the ab initio polyatomic program HONDO are extended to the coupled perturbed Hartree–Fock (CPHF) formalism, a key step in the analytical computation of energy first derivatives for configuration interaction (CI) wavefunctions, and energy second derivatives for Hartree–Fock (HF) wavefunctions. One possible computational strategy is to construct Fock-like matrices for each nuclear coordinate in which the one- and two-electron integrals of the usual Fock matrix are replaced by the integral first derivatives. “Skeleton” matrices are constructed from the unique blocks of electron-repulsion integral derivatives. The correct matrices are generated by applying a symmetrization operator. The analysis is valid for many wavefunctions, including closed- or open-shell spin-restricted and spin-unrestricted HF wavefunctions. To illustrate the method, we compare the computer time required for setting up the coupled perturbed HF equations for eclipsed ethane using D_3h symmetry point group and various subgroups of D_3h. Computational times are roughly inversely proportional to the order of the point group.     

Synthesis of a novel hybrid liquid‐crystalline rod–coil diblock copolymer

A series of novel rod–coil diblock copolymers on the basis of mesogen‐jacketed liquid‐crystalline polymer were successfully prepared by atom transfer radical polymerization from the flexible polydimethylsiloxane (PDMS) macroinitiator. The hybrid diblock copolymers, poly{2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene}‐block‐polydimethylsiloxane, had number‐average molecular weights (M_n's) ranging from 9500 to 30,900 and relatively narrow polydispersities (≤1.34). The polymerization proceeded with first‐order kinetics. Data from differential scanning calorimetry validated the microphase separation of the diblock copolymers. All block copolymers exhibited thermotropic liquid‐crystalline behavior except for the one with M_n being 9500. Four liquid‐crystalline diblock copolymers with PDMS weight fractions of more than 18% had two distinctive glass‐transition temperatures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1799–1806, 2003     

Syntheses and properties of new aromatic polybenzoxazoles bearing ether and phenylethylidene or 1‐phenyl‐2,2,2‐trifluoroethylidene linkages

Two new bis(ether acyl chloride)s, 1,1‐bis[4‐(4‐chloroformylphenoxy)phenyl]‐1‐phenylethane and 1,1‐bis[4‐(4‐chloroformylphenoxy)phenyl]‐1‐phenyl‐2,2,2‐trifluoroethane, were prepared from readily available reagents. Aromatic polybenzoxazoles with both ether and phenylethylidene or 1‐phenyl‐2,2,2‐trifluoroethylidene linkages between phenylene units were obtained by a conventional two‐step procedure including the low‐temperature solution polycondensation of the bis(ether acyl chloride)s with three bis(o‐aminophenol)s, yielding poly(o‐hydroxyamide) precursors, and subsequent thermal cyclodehydration. The intermediate poly(o‐hydroxyamide)s exhibited inherent viscosities of 0.39–0.98 dL/g. All of the poly(o‐hydroxyamide)s were amorphous and soluble in polar organic solvents such as N,N‐dimethylacetamide, and most of them could afford flexible and tough films via solvent casting. The poly(o‐hydroxyamide)s exhibited glass‐transition temperatures (T_g's) of 129–194 °C and could be thermally converted into corresponding polybenzoxazoles in the solid state at temperatures higher than 300 °C. All the polybenzoxazoles were amorphous and showed an enhanced T_g but a dramatically decreased solubility with to respect to their poly(o‐hydroxyamide) precursors. They exhibited T_g's of 216–236 °C through differential scanning calorimetry and were stable up to 500 °C in nitrogen or air, with 10% weight‐loss temperatures being recorded between 538 and 562 °C in nitrogen or air. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 914–921, 2003     

MPI/OpenMP hybrid parallel algorithm for resolution of identity second‐order Møller–Plesset perturbation calculation of analytical energy gradient for massively parallel multicore supercomputers

A massively parallel algorithm of the analytical energy gradient calculations based the resolution of identity Møller–Plesset perturbation (RI‐MP2) method from the restricted Hartree–Fock reference is presented for geometry optimization calculations and one‐electron property calculations of large molecules. This algorithm is designed for massively parallel computation on multicore supercomputers applying the Message Passing Interface (MPI) and Open Multi‐Processing (OpenMP) hybrid parallel programming model. In this algorithm, the two‐dimensional hierarchical MP2 parallelization scheme is applied using a huge number of MPI processes (more than 1000 MPI processes) for acceleration of the computationally demanding O (N ⁵) step such as calculations of occupied–occupied and virtual–virtual blocks of MP2 one‐particle density matrix and MP2 two‐particle density matrices. The new parallel algorithm performance is assessed using test calculations of several large molecules such as buckycatcher C₆₀@C₆₀H₂₈ (144 atoms, 1820 atomic orbitals (AOs) for def2‐SVP basis set, and 3888 AOs for def2‐TZVP), nanographene dimer (C₉₆H₂₄)₂ (240 atoms, 2928 AOs for def2‐SVP, and 6432 AOs for cc‐pVTZ), and trp‐cage protein 1L2Y (304 atoms and 2906 AOs for def2‐SVP) using up to 32,768 nodes and 262,144 central processing unit (CPU) cores of the K computer. The results of geometry optimization calculations of trp‐cage protein 1L2Y at the RI‐MP2/def2‐SVP level using the 3072 nodes and 24,576 cores of the K computer are presented and discussed to assess the efficiency of the proposed algorithm. © 2017 Wiley Periodicals, Inc.     

One‐particle density matrix functional for correlation in molecular systems

Based on the analysis of the general properties for the one‐ and two‐particle reduced density matrices, a new natural orbital functional is obtained. It is shown that by partitioning the two‐particle reduced density matrix in an antisymmeterized product of one‐particle reduced density matrices and a correction Γ^c we can derive a corrected Hartree–Fock theory. The spin structure of the correction term from the improved Bardeen–Cooper–Schrieffer theory is considered to take into account the correlation between pairs of electrons with antiparallel spins. The analysis affords a nonidempotent condition for the one‐particle reduced density matrix. Test calculations of the correlation energy and the dipole moment of several molecules in the ground state demonstrate the reliability of the formalism. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 317–323, 2003     

Aminated PCL‐based copolymers by chemical modification of poly(α‐iodo‐ε‐caprolactone‐co‐ε‐caprolactone)

A novel method is proposed to access to new poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) using poly(α‐iodo‐ε‐caprolactone‐co‐ε‐caprolactone) as polymeric substrate. First, ring‐opening (co)polymerizations of α‐iodo‐ε‐caprolactone (αIεCL) with ε‐caprolactone (εCL) are performed using tin 2‐ethylhexanoate (Sn(Oct)₂) as catalyst. (Co)polymers are fully characterized by ¹H NMR, ¹³C NMR, FTIR, SEC, DSC, and TGA. Then, these iodinated polyesters are used as polymeric substrates to access to poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) by two different strategies. The first one is the reaction of poly(αIεCL‐co‐εCL) with ammonia, the second one is the reduction of poly(αN₃εCL‐co‐εCL) by hydrogenolysis. This poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) (F_αNH2εCL < 0.1) opens the way to new cationic and water‐soluble PCL‐based degradable polyesters. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6104–6115, 2009     

One‐pot synthesis of 1‐ and 5‐substituted 1H‐tetrazoles using 1,4‐dihydroxyanthraquinone–copper(II) supported on superparamagnetic Fe3O4@SiO2 magnetic porous nanospheres as a recyclable catalyst

An effective one‐pot, convenient process for the synthesis of 1‐ and 5‐substituted 1H‐tetrazoles from nitriles and amines is described using1,4‐dihydroxyanthraquinone–copper(II) supported on Fe₃O₄@SiO₂ magnetic porous nanospheres as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields. The preparation of the magnetic nanocatalyst with core–shell structure is presented by using nano‐Fe₃O₄ as the core, tetraethoxysilane as the silica source and poly(vinyl alcohol) as the surfactant, and then Fe₃O₄@SiO₂ was coated with 1,4‐dihydroxyanthraquinone–copper(II) nanoparticles. The new catalyst was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometry, X‐ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm analysis and inductively coupled plasma analysis. This new procedure offers several advantages such as short reaction times, excellent yields, operational simplicity, practicability and applicability to various substrates and absence of any tedious workup or purification. In addition, the excellent catalytic performance, thermal stability and separation of the catalyst make it a good heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Photocrosslinked poly(vinylbenzophenone)‐core micelles via mild Friedel–Crafts benzoylation of polystyrene amphiphiles

Photocrosslinkable poly(vinylbenzophenone)‐containing polymers were synthesized via a one‐step, Friedel–Crafts benzoylation of polystyrene‐containing starting materials [including polystyrene, polystyrene‐block‐poly(tert‐butyl acrylate), polystyrene‐block‐poly(ethylene oxide), polystyrene‐block‐poly(methyl methacrylate), and polystyrene‐block‐poly(n‐butyl acrylate)] with benzoyl trifluoromethanesulfonate as a benzoylation reagent. The use of this mild reagent (which required no added Lewis acid) permitted polymers with well‐defined compositions and narrow molecular weight distributions to be synthesized. Micelles formed from one of these benzoylated polymers, [polystyrene_0.25‐co‐poly(vinylbenzophenone)_0.75]₁₁₅‐block‐poly(acrylic acid)₁₄, were then fixed by the irradiation of the micelle cores with UV light. As the irradiation time was increased, the pendent benzophenone groups crosslinked with other chains in the glassy micelle cores. Dynamic light scattering, spectrofluorimetry, and Fourier transform infrared spectroscopy were all used to verify the progress of the crosslinking reaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2604–2614, 2006     

Tailoring the Structure of Two‐Dimensional Self‐Assembled Nanoarchitectures Based on NiII–Salen Building Blocks

The synthesis of a series of Ni^II–salen‐based complexes with the general formula of [Ni(H₂L)] (H₄L=R²‐N,N′‐bis[R¹‐5‐(4′‐benzoic acid)salicylidene]; H₄L1: R²=2,3‐diamino‐2,3‐dimethylbutane and R¹=H; H₄L2: R²=1,2‐diaminoethane and R¹=tert‐butyl and H₄L3: R²=1,2‐diaminobenzene and R¹=tert‐butyl) is presented. Their electronic structure and self‐assembly was studied. The organic ligands of the salen complexes are functionalized with peripheral carboxylic groups for driving molecular self‐assembly through hydrogen bonding. In addition, other substituents, that is, tert‐butyl and diamine bridges (2,3‐diamino‐2,3‐dimethylbutane, 1,2‐diaminobenzene or 1,2‐diaminoethane), were used to tune the two‐dimensional (2D) packing of these building blocks. Density functional theory (DFT) calculations reveal that the spatial distribution of the LUMOs is affected by these substituents, in contrast with the HOMOs, which remain unchanged. Scanning tunneling microscopy (STM) shows that the three complexes self‐assemble into three different 2D nanoarchitectures at the solid–liquid interface on graphite. Two structures are porous and one is close‐packed. These structures are stabilized by hydrogen bonds in one dimension, while the 2D interaction is governed by van der Waals forces and is tuned by the nature of the substituents, as confirmed by theoretical calculations. As expected, the total dipolar moment is minimized     

Equations de Hartree–Fock dependant du temps

The time-dependent Hartree–Fock (TDHF ) equations are derived up to the second order when the system is perturbed by a monochromatic plane wave. The solutions of the equations are subjected to the orthonormalization conditions satisfied by the orbitals. In the equations, these conditions are expressed by the appearing of coefficients λ playing the part of Lagrangian multipliers. Relations between the coefficients λ are established. These relations are equivalent to the above-mentioned orthonormalization conditions. This equivalence enables us to substitute for the solution of an integrodifferential equation system subject to constraint conditions, that of a free system. The TDHF equations obtained determine the first- and second-order orbital perturbations, which no doubt verify the orthonormalization conditions. These orbitals can be used in the calculation, up to second order, of different nonlinear optical effects.     

Synthesis and properties of the ionomer diblock copolymer poly(4‐vinylbenzyl triethyl ammonium bromide)‐b‐polyisobutene

A new amphiphilic diblock copolymer containing an ionomer segment, poly[(4‐vinylbenzyl triethyl ammonium bromide)‐co‐(4‐methylstyrene)‐co‐(4‐bromomethylstyrene)]‐b‐polyisobutene [poly(4‐VBTEAB)‐b‐PIB], was synthesized by the chemical modification of poly(4‐methylstyrene)‐b‐polyisobutene [poly(4‐MSt)‐b‐PIB]. First, the 4‐methylstyrene moiety in poly(4‐MSt)‐b‐PIB was brominated with azobisisobutyronitrile as an initiator at 60 °C in CCl₄, and then the highly reactive benzyl bromide groups were ionized by a reaction with triethylamine in a toluene/isopropyl alcohol (80/20 v/v) mixture at about 85 °C to produce the ionomer diblock copolymer poly(4‐VBTEAB)‐b‐PIB. The solubility of the ionomer block copolymer was quite different from that of the corresponding poly[(4‐methylstyrene)‐co‐(4‐bromomethylstyrene)]‐b‐polyisobutene {poly[(4‐MSt)‐co‐(4‐BrMSt)]‐b‐PIB}. Transmission electron microscopy observations demonstrated that all three diblock copolymers had microphase‐separation structures in which polyisobutene (PIB) domains existed in the continuous phase of the poly(4‐methylstyrene) segment or its derivative segment matrix. Dynamic mechanical thermal analysis measurements showed that poly[(4‐MSt)‐co‐(4‐BrMSt)]‐b‐PIB had two glass‐transition temperatures (T_g's), ?56 °C for the PIB segment and 62 °C for the poly[(4‐MSt)‐co‐(4‐BrMSt)] domain, whereas poly(4‐VBTEAB)‐b‐PIB showed one T_g at ?8 °C of the PIB domain; T_g of the poly[(4‐vinylbenzyl triethyl ammonium bromide)‐co‐(4‐methylstyrene)‐co‐(4‐bromomethylstyrene)] domain was not observable because of the strong ionic interactions resulting in a higher T_g and a retention of modulus up to 124 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2755–2764, 2003     

Hyperbranched polymers as scaffolds for multifunctional reversible addition–fragmentation chain‐transfer agents: A route to polystyrene‐core‐polyesters and polystyrene‐block‐poly(butyl acrylate)‐core‐polyesters

Polydisperse hyperbranched polyesters were modified for use as novel multifunctional reversible addition–fragmentation chain‐transfer (RAFT) agents. The polyester‐core‐based RAFT agents were subsequently employed to synthesize star polymers of n‐butyl acrylate and styrene with low polydispersity (polydispersity index < 1.3) in a living free‐radical process. Although the polyester‐core‐based RAFT agent mediated polymerization of n‐butyl acrylate displayed a linear evolution of the number‐average molecular weight (M_n) up to high monomer conversions (>70%) and molecular weights [M_n > 140,000 g mol^?1, linear poly(methyl methacrylate) equivalents)], the corresponding styrene‐based system reached a maximum molecular weight at low conversions (≈30%, M_n = 45,500 g mol^?1, linear polystyrene equivalents). The resulting star polymers were subsequently used as platforms for the preparation of star block copolymers of styrene and n‐butyl acrylate with a polyester core with low polydispersities (polydispersity index < 1.25). The generated polystyrene‐based star polymers were successfully cast into highly regular honeycomb‐structured microarrays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3847–3861, 2003     

DFT study of ferroelectric properties of the copolymers: Poly(vinylideneflouride‐trifluoroethylene) and poly(vinylidene fluoride‐chlorotrifluoroethylene)

A theoretical study of poly(vinylidene flouride‐trifluoroethylene) and poly(vinylidene fluoride‐chlorotrifluoroethylene, is presented. By density functional theory calculations, some of the properties of these materials have been obtained. Among such properties, the dipolar moment and the energies associated to the structural changes. The B3LYP functional and 6311+G(d,p) bases set were used with Gaussian program. Calculations associated to different conformations were carried out to get insight about the involved phase changes. The energetic, charges, and dipole moment were calculated. The conformations, namely, I = T_p, II = TG_a, and III = TG_p, where T means trans and G means gauche, for the two polymers aforementioned were compared with the poly(vinilydene fluoride) studies previously obtained. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2411–2417, 2010     

Kinetic and mechanistic studies of the oxidation of poly(o‐toluidine) doped with 5‐sulfosalicylic acid

Protonation of poly(o‐toluidine) base form (POT‐EB) with 5‐sulfosalicylic acid (SSA) was proved experimentally and computationally. Molecular mechanics (MM+) calculations showed that the potential energy (PE) of the optimum molecular geometric structure of SSA‐doped POT is 4.703 × 10³ kcal mol^?1 or at least three orders of magnitude higher than the PE of the molecular geometric structure of the same matrix. These calculations indicate that the optimization of this matrix is necessary for understanding the stability. Dark green coloration (λ ～800 nm) after addition of SSA into POT‐EB matrix (dark blue, λ ～600 nm) revealed that the SSA was working as a protonating agent to convert POT base form (POT‐EB) to salt form (SSA‐doped POT). The change of the dark green color of SSA‐doped POT to dark brown (λ ～500 nm) after addition of oxidant (K₂CrO₄) was due to the highest oxidized form of the matrix obtained (the quinoid one), which undergoes a hydrolysis reaction to produce p‐hydroquinone (H₂Q) by a mechanism similar to Schiff‐base hydrolysis. Kinetic parameters of the oxidation reaction were deduced employing a computer‐aided kinetic analysis of the absorbance (A) at ～800 nm against the hydrolysis time (t) data. The results obtained indicate that the rate controlling process may be governed by the Ginstling–Brounshetin equation for three‐dimensional diffusion (D4). The proposed mechanism for the oxidation of SSA‐doped POT matrix is also supported by MM+ calculations. Activation parameters for the rate of the oxidation process of acid‐doped POT matrix have been computed and discussed. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 260–272, 2003     

Morphology of poly(butylene terephthalate)–poly(ethylene terephthalate‐co‐isophthalate‐co‐sebacate) segmented copolyesters

Segmented copolyesters, namely, poly(butylene terephthalate)–poly(ethylene terephthalate‐co‐isophthalate‐co‐sebacate) (PBT‐PETIS), were synthesized with the melting transesterification processing in vacuo condition involving bulk polyester produced on a large scale (PBT) and ternary amorphous random copolyester (PETIS). Investigations on the morphology of segmented copolyesters were undertaken. The two‐phase morphology model was confirmed by transmission electron microscopy and dynamic mechanical thermal analysis. One of the phases was composed of crystallizable PBT, and the other was a homogeneous mixture of PETIS and noncrystallizable PBT. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2257–2263, 2003     

Stable second‐order nonlinear optical poly(amide–imide)/inorganic materials via simultaneous sequential self‐repetitive reaction and sol–gel process

A series of thermally stable organic/inorganic second‐order nonlinear optical (NLO) composites via sequential self‐repetitive reaction (SSRR) and sol–gel process has been developed. This SSRR is based on carbodiimide (CDI) chemistry. The difunctional azo chromophores (2,4‐diamino‐4′‐(4‐ nitrophenyl‐diazenyl)azobenzene (DNDA)) was reacted with excessive amount of 4, 4′‐methylene‐ diphenylisocyanate (MDI) to form poly‐CDI, and subsequently trimellitic anhydride (TMA) was added to obtain poly(N‐acylurea). The organic/inorganic composites containing prepolymer of phenyltriethoxysilane (PTEOS) and poly(N‐acylurea) in different weight ratios (10:90, 30:70, 50:50, 70:30, 90:10 wt%) were prepared, respectively. The moderate glass transition temperature (T_g) characteristic of the poly(N‐acylurea) allows the NLO‐active polymer to achieve high poling efficiency. After in situ poling and curing process, the T_gs of the composites were elevated, and higher than that of the pristine poly(amide–imide) sample. Electro‐optical (EO) coefficients (r₃₃) of about 5.5 ～ 18.0 pm/V at 830 nm were obtained. Excellent temporal stability at 100°C, and waveguide characteristics (3.1–4.2 dB/cm at 830 nm) were also obtained for these composites. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and morphology of polyethylene‐block‐poly(methyl methacrylate) through the combination of metallocene catalysis with living radical polymerization

Polyethylene‐block‐poly(methyl methacrylate) (PE‐b‐PMMA) was successfully synthesized through the combination of metallocene catalysis with living radical polymerization. Terminally hydroxylated polyethylene, prepared by ethylene/allyl alcohol copolymerization with a specific zirconium metallocene/methylaluminoxane/triethylaluminum catalyst system, was treated with 2‐bromoisobutyryl bromide to produce terminally esterified polyethylene (PE‐Br). With the resulting PE‐Br as an initiator for transition‐metal‐mediated living radical polymerization, methyl methacrylate polymerization was subsequently performed with CuBr or RuCl₂(PPh₃)₃ as a catalyst. Then, PE‐b‐PMMA block copolymers of different poly(methyl methacrylate) (PMMA) contents were prepared. Transmission electron microscopy of the obtained block copolymers revealed unique morphological features that depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50–100‐nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix. Moreover, the PE‐b‐PMMA block copolymers effectively compatibilized homopolyethylene and homo‐PMMA at a nanometer level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3965–3973, 2003     

One‐pot,solvent‐free,metal‐free synthesis and UCST‐based purification of poly(ethylene oxide)/poly‐ε‐caprolactone block copolymers

A fast, one pot, solvent‐free and metal‐free synthesis of poly‐ε‐caprolactone and poly(ethylene oxide) block copolymers is reported. Copolymers with different molar mass, different hydrophilic to lipophilic balance, high degree of conversion and narrow molar mass dispersity have been obtained by organocatalyzed ring opening polymerization of ε‐caprolactone in presence of mono‐ or diol‐poly(ethylene oxide) as initiator and fumaric acid as catalyst. A new biocompatible and environmental friendly purification method is presented, exploiting the upper critical solution temperature of these class of copolymers in ethanol. The phase diagrams of the synthesized copolymers in ethanol are also reported. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2992–2999     

Facile synthesis of linear–hyperbranched polyphosphoesters via one‐pot tandem ROMP and ADMET polymerization and their transformation to architecturally defined nanoparticles

A convenient one‐pot synthesis of linear–hyperbranched polyphosphoesters (l–HBPPEs) was accomplished by a tandem ring‐opening metathesis polymerization (ROMP) and acyclic diene metathesis (ADMET) polymerization procedure. A linear monotelechelic poly(norbornene) with a terminal acrylate and many pendent thiol groups is first prepared through adding an internal cis‐olefin terminating agent to the reaction mixture immediately after the completion of the living ROMP, and then utilized as a macromolecular chain stopper in subsequent ADMET polymerization of a phosphoester functional AB₂ monomer, yielding l–HBPPEs as the reaction time prolonged. These l–HBPPEs bearing lots of pendent thiol groups in linear poly(norbornene) and peripheral acrylate groups in HBPPE could be self‐crosslinked in ultradilute solution through thiol‐Michael addition click reaction between acrylate and thiol to give single‐molecule nanoparticles with comparatively uniform size. This facile approach can be extended toward the fabrication of novel nanomaterials with sophisticated structures and tunable multifunctionalities. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 964–972     

Facile Synthesis and Structural Characterization by NMR,ESI–MS/MS and DFT Calculations of New (E)‐6‐[2‐Ferrocenylalkylidenehydrazino]nicotinic Hydrazides and Their (E)‐Ferrocenyl‐pyrazolyl‐pyridine Heterocyclic System

This paper reports a facile and convenient access by a conventional thermal procedure in ethanol as solvent to a new examples of (E)‐6‐[2‐ferrocenylalkylidenehydrazino]nicotinic hydrazides ( 3 ) (53–72%) from the quimioselective reactions of 6‐hydrazinonicotinc hydrazide ( 1 ) with acylferrocenes ( 2 ), where acyl = formyl and acetyl. Subsequently, cyclocondensation reactions of ferrocenylalkylidene hydrazones ( 3 ) with 4‐R¹‐4‐alkoxy‐1,1,1‐trifluoroalk‐3‐en‐2‐ones ( 4 ), where R¹ = Me, Ph, 2‐Furyl, to obtain new six heterocyclic derivatives as (E)‐pyrazolyl‐pyridinohydrazones ( 5 ) (58–63%), are also presented. The structures of these new heterocyclic compounds 5 containing an organometallic unit were characterized and studied by NMR, ESI–MS/MS techniques. DFT calculations were also employed to assign the E configuration for compounds 3 and 5 .