Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription Mo(CO) 6 from 1.0 equiv (43% conversion, entry 1 in Table 149 1) to 0.5 equiv (67% conversion, entry 2 in 199 This good trans-diastereoselectivity is remarkable, revealing a 200 marked preference for C−H activation of the pro-S methyl 201 group of (+)-3.23e Importantly, the major (−)-trans-9 202 diastereomer could be isolated in 75% yield with no appreciable 203 loss of enantiopurity (97% ee) upon standard chromatography. 204Although the structure of the bimetallic complex of γ-205 cyclopalladation of tert-leucine derivative (+)-1 (complex A) 206 strongly suggested that the NH−SO 2 Py directing group is 207 crucial for this transformation, we were interested in confirming 208 this issue by screening other potentially coordinating N-209 protecting groups. For this purpose, a set of L-valine derivatives 210 (substrates 4−8) were examined in the carbonylation reaction 211 under the optimized conditions, and the results are summarized 212 in Table 2. While L-valine methyl ester hydrochloride 213 decomposed under the reaction conditions (entry 2 in Table 214 2), the NH-Ts derivative 5 and the NH-(2-thienyl)sulfonyl 215 derivative 6 were recovered unaltered without detecting any 216 carbonylation product (entries 3 and 4, respectively, in Table 217 2). The reaction of the (8-quinolyl)sulfonyl and (2-pyridyl)-218 carbonyl derivatives (7 and 8, respectively) led to a complex 219 mixture of products in low conversion (<10%) (entries 5 and 6 220 in Table 2). Interestingly, the lack of reaction efficiency 87 (75) e 5.7:1 (9) 9 7 2 −(4)a Reaction conditions are identical to those given in Table 1 This method was extended to β-amino acid derivatives, as 260 exemplified by the clean cyclocarbonylation of β-amino ester 261 (±)-19, affording the product (±)-20 as a separable 3.8:1 262 mixture of trans/cis diastereoisomers in good overall yield 263 (76%). 264Extension of the Method to Simple Aliphatic Amines. 265 The broad substrate scope displayed by this reaction with α-266 amino acid derivatives prompted us to explore the extension of 267 this method to simple aliphatic amine derivatives. We first 268 tested if compound (−)-21, analogue to tert-leucine derivative 269 1 but lacking the methyl ester moiety, could undergo γ-270 cyclometalation. The stoichiometric reaction of (−)-21 with 271 Pd(OAc) 2 (1.0 equiv) in acetonitrile at 60°C for 3.5 h, cleanly 272 provided, after simple recrystallization, the expected bimetallic 273 complex B in 91% yield (unambiguously determined by singles3 274 crystal X-ray diffraction (XRD) analysis; see Scheme 3), which 275 presents an analogous structure to complex A. This result demonstrated that the ester group at the α-277 position of the previously studied α-amino ester derivatives was 278 not essential for the C−H activation step. Fu...

Spin crossover (SCO) molecules are promising nanoscale magnetic switches due to their ability to modify their spin state under several stimuli. However, SCO systems face several bottlenecks when downscaling into nanoscale spintronic devices: their instability at the nanoscale, their insulating character and the lack of control when positioning nanocrystals in nanodevices. Here we show the encapsulation of robust Fe-based SCO molecules within the 1D cavities of single-walled carbon nanotubes (SWCNT). We find that the SCO mechanism endures encapsulation and positioning of individual heterostructures in nanoscale transistors. The SCO switch in the guest molecules triggers a large conductance bistability through the host SWCNT. Moreover, the SCO transition shifts to higher temperatures and displays hysteresis cycles, and thus memory effect, not present in crystalline samples. Our results demonstrate how encapsulation in SWCNTs provides the backbone for the readout and positioning of SCO molecules into nanodevices, and can also help to tune their magnetic properties at the nanoscale.

The formation of discrete macrocycles wrapped around single-walled carbon nanotubes (SWCNTs) has recently emerged as an appealing strategy to functionalize these carbon nanomaterials and modify their properties.H ere,w e demonstrate that the reversible disulfide exchange reaction, which proceeds under mild conditions,c an install relatively large amounts of mechanically interlocked disulfide macrocycles on the one-dimensional nanotubes.S ize-selective functionalization of am ixture of SWCNTs of different diameters were observed, presumably arising from error correction and the presence of relatively rigid, curved p-systems in the key building blocks.Acombination of UV/Vis/NIR, Raman, photoluminescence excitation, and transient absorption spectroscopyindicated that the small (6,4)-SWCNTs were predominantly functionalizedbythe small macrocycles 1 2 ,whereas the larger (6,5)-SWCNTs were an ideal matchf or the larger macrocycles 2 2 .T his sizes electivity,w hich was rationalized computationally,c ould prove useful for the purification of nanotube mixtures,s ince the disulfide macrocycles can be removed quantitatively under mild reductive conditions.

We report the isolation of thin flakes of cylindrite, a naturally occurring van der Waals superlattice, by means of mechanical and liquid phase exfoliation. We find that this material is a heavily doped p-type semiconductor with a narrow gap (<0.85 eV) with intrinsic magnetic interactions that are preserved even in the exfoliated nanosheets. Due to its environmental stability and high electrical conductivity, cylindrite can be an interesting alternative to the existing two-dimensional magnetic materials.

van der Waals heterostructures (vdWH) are made of different two-dimensional (2D) layers stacked on top of each other, forming a single material with unique properties that differ from those of the individual 2D constituent layers, and that can be modulated through the interlayer interaction. These hetero-materials can be artificially made by mechanical stamping, solution processing or epitaxial growth. Alternatively, franckeite has been recently described as an example of a naturally-occurring vdWH that can be exfoliated down to nanometer thicknesses. Research on vdWHs has so far been limited to manually exfoliated and stamped individual devices. Here, a scalable and fast method to fabricate vdWH nanodevices from liquid phase exfoliated nanoflakes is reported. The transport and positioning of the flakes into localized submicrometer structures is achieved simultaneously in multiple devices via a dielectrophoretic process. The complex vdWH is preserved after dielectrophoresis and the properties of the resulting field-effect transistors are equivalent to those fabricated via mechanical exfoliation and stamping. The combination of liquid phase exfoliation and dielectrophoretic assembly is particularly suited for the study of vdWHs and applications where large-scale fabrication is required.