The nonuniform molecular architecture of ethylene/1-octene multiblock copolymers (O-MBCs) synthesized by the chain shuttling technology is investigated. The samples consist of chains characterized by alternating hard (crystalline) and soft (amorphous) blocks, corresponding to random ethylene/1-alkene copolymers with a low and high comonomer content, respectively. The chains are nonuniform as the distribution in the length and number of blocks per chain are statistical and vary from chain to chain. A clear-cut investigation of the inter- and intrachain constitutional heterogeneity of O-MBCs is performed by carrying out, at first, a sequential and exhaustive solvent fractionation procedure in boiling solvents, that is, diethyl ether, n-hexane, and cyclohexane. Successively, the unfractionated samples and the corresponding fractions are subjected to analytical crystallization elution fractionation (aCEF), solution 13C NMR, differential scanning calorimetry, and wide- and small-angle X-ray scattering (SAXS) analyses. Four fractions of increasing average ethylene content, hard block content, and degree of crystallinity are obtained, that is, a fraction soluble in diethyl ether (sEE), a fraction insoluble in diethyl ether/soluble in n-hexane (iEE-sC6), a fraction insoluble in n-hexane/soluble in cyclohexane (iC6-sCC6), and a fraction insoluble in cyclohexane (iCC6). The results of aCEF and 13C NMR analysis highlight that the multiblock chain microstructure of the O-MBCs corresponds to a statistical distribution of the length of hard and soft blocks that occurs not only at an interchain level but also at an intrachain level. SAXS measurements essentially confirm the results of the microstructural analysis and allow achieving a quantitative description of the constitutional heterogeneity affecting O-MBCs at the intramolecular level. In particular, it is shown that for the inferior fractions (sEE and iEE-sC6), the chains include hard blocks of low molecular mass (<1 kDa) covalently linked to short and long soft blocks in the iEE-sC6 and sEE fractions, respectively. For the superior fractions (iC6-sCC6 and iCC6), instead, it is shown that the chains include hard blocks of significantly different molecular masses that experience molecular fractionation by the effect of crystallization, the molecular mass of the hard M H and soft M S blocks in the HS units being comprised in between 2 and 16 and 6 and 44 kDa, respectively. These characteristics explain quite well the fractionation behavior of the O-MBCs, highlighting that the solubility in a given solvent does not depend exclusively on the length and the content of hard blocks but is critically dependent also on the length and content of soft blocks.

We present a generalization of a self-consistent electrostatic embedding approach (SC-Ewald) devised to investigate the photophysical properties of 3D periodic materials, to systems in one-or two-dimensional (2D) reduced periodicity. In this approach, calculations are carried out on a small finite molecular cluster extracted from a periodic model, while the crystalline environment is accounted for by an array of point charges which are fitted to reproduce the exact electrostatic potential (at ground or the excited state) of the infinite periodic system. Periodic density functional theory (DFT) calculations are combined with time dependent DFT calculations to simulate absorption and emission properties of the extended system under investigation. We apply this method to compute the UV-Vis. spectra of bulk and quantumconfined 0D quantum dots and 2D extended nanoplatelets of CdSe, due to their relevance as sensitizers in solar cells technologies. The influence of the size and shape of the finite cluster model chosen in the excited state calculations was also investigated and revealed that, although the long-range electrostatics of the environment are important for the calculation of the UV-Vis, a subtle balance between short-and long-range effects exists. These encouraging results demonstrate that this self-consistent electrostatic embedding approach, when applied in different dimensions, can successfully model the photophysical properties of diverse material classes, making it an attractive low-cost alternative to far more computationally demanding electronic structure methods for excited state calculations.

A copper-mediated coupling reaction between ynamides and diazo-compounds to produce N-allenamides is reported for the first time. This method enables facile and rapid access to terminal N-allenamides by using commercially available TMS-diazomethane with wide functional group compatibility on the nitrogen. Furthermore, the ubiquity of [a

The significance of molecules containing difluoromethyl groups is driven by their potential applications in pharmaceutical and agrochemical science. Methods for the incorporation of lightly fluorinated groups such as -CF 2 H are less well developed. Here we report the use of difluorinated diazoacetone as a practical reagent for the direct synthesis of CF 2 H-substituted 2amido-furans through addition to ynamides. These newly designed difluorinated amidofurans were elaborated to create new nitrogen-containing frameworks that would be challenging to obtain otherwise. c yield of the two-step process: deprotection of the ynamide and cyclization.