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In this work, we explain the origin and the mechanism responsible for the strong enhancement of the Raman signal of sulfur chains encapsulated by single-wall carbon nanotubes by running resonance Raman measurements in a wide range of excitation energies for two nanotube samples with different diameter distributions. The Raman signal associated with the vibrational modes of the sulfur chain is observed when it is confined by small-diameter metallic nanotubes. Moreover, a strong enhancement of the Raman signal is observed for excitation energies corresponding to the formation of excited nanotube-chain-hybrid electronic states. Our hypothesis was further tested by high pressure Raman measurements and confirmed by density functional theory calculations of the electronic density of states of hybrid systems formed by sulfur chains encapsulated by different types of single-wall carbon nanotubes.

Purpose There is concern that graduating surgery residents are not prepared for independent practice. This study aimed to identify predictors of performance, autonomy, and readiness for independence ratings of trainees by attendings for thyroidectomy and parathyroidectomy with respect to repeated resident-attending exposure. We hypothesized that increased exposure with a particular attending increases resident autonomy. Methods All residents and faculty at a single institution performing parathyroidectomy or thyroidectomy were invited to complete an operative performance evaluation at case competition using the Zwisch scale to measure performance and autonomy for individual operative steps. In addition, each survey evaluated the trainee's readiness for practice in a straightforward procedure as a binary variable. Categorical variables were evaluated via Chi-squared or Fisher's exact tests and ordinal variables were evaluated with Wilcoxon or Kruskal-Wallis tests. Multivariable analysis was conducted with random effects logistic regression, and learning curves were generated for each procedure. Results Operative performance evaluations were obtained from 36 individual learners and 6 faculty members, with a total of 145 evaluations for parathyroidectomy and 116 for thyroidectomy. On bivariate analysis, readiness for practice ratings was significantly associated with increasing chronologic procedure number, but not resident gender or case difficulty. The multivariable model demonstrated that increasing chronologic procedure number, while a significant predictor without accounting for exposure, did not remain a significant predictor of practice-readiness for parathyroidectomy when accounting for resident-attending exposure. Bivariate analysis comparing resident and attending ratings showed no difference between the 2, but there were significant differences in autonomy and performance scores for both groups of raters. Trainees rated by attendings as independence ready completed a median of 7 parathyroidectomies and 5 thyroidectomies. Descriptive learning curves generated serve as a model of the multistate nature that residents undergo when moving from novice to proficiency. Conclusions Not surprisingly, the more operations residents perform with a single attending, the higher their ratings for performance and autonomy from that individual, with increased exposure allowing improved performance with less attending autonomy. By contrast, our data also show that repeated exposure between resident and attending may confound the use of procedural numbers alone when predicting resident ability in the operating room.

Alignment of densely packed single-walled carbon nanotubes (SWNTs) largely preserves the extraordinary electronic properties of individual SWNTs in the alignment direction, while in transverse direction the films are very resistive due to large energy barriers for tunneling between adjacent SWNTs. We demonstrate that chromium atoms inserted between the sidewalls of parallel SWNTs effectively coordinate to the benzene rings of the nanotubes via hexahapto bonds that preserve the nanotube-conjugated electronic structure and serve as a conduit for electron transfer. The atomically interconnected aligned SWNTs exhibit enhanced transverse conductivity, which increases by ∼2100% as a result of the photoactivated organometallic functionalization with Cr. The hexahapto mode of bonding the graphitic surfaces of carbon nanotubes with transition metal atoms offers an attractive route to the reversible chemical engineering of the transport properties of aligned carbon nanotube thin films. We demonstrate that a device fabricated with aligned SWNTs can be reversibly switched between a state of high electrical conductivity (ON) by light and low electrical conductivity (OFF) by applied potential. This study provides a route to the design of novel nanomaterials for applications in electrical atomic switches, optoelectronic and spintronic devices.

We report the experimental realization of η6-complexes of group 6 transition metals with a single layer graphene using photo-activated reactions with organometallic compounds. The reaction progress was followed by in-situ measurements of the graphene conductivity. We observed that the chromium reagents exert the strongest effect on the electronic properties of graphene, leading to (η6-graphene)CrL [L = C6H6, (CO)3] complexes with enhanced conductivity. Thus, in the case of covalent functionalization of graphene with Cr(CO)6, the conductivity increased by a factor of 4, while the (η6- C6H6)Cr(CO)3 reagent doubled the conductivity producing the least enhancement. This mode of covalent bonding preserves the conjugation and the planarity of the graphene structure and offers a promising route for the preparation of a new class of graphitic materials functionalized with transition metals, which may find applications in optoelectronics, spintronics and magnetic nanodevices.

INTRODUCTION: Citation count is a common bibliometric tool used to determine long-term impact and performance of journal articles. Many of the other potential factors associated with highly and lowly cited articles in the general surgery literature, however, remain unknown. The purpose of this study was to attempt to identify characteristics of articles that may predict or correlate with article citation counts and, consequently, article impact. METHODS: We identified articles from Annals of Surgery, British Journal of Surgery, and Journal of the American College of Surgeons between 1998 and 2008 that had 0–5 total citations. We then matched these articles to an identical number of the highest cited articles from these same journals for comparison. Student’s t tests, Wilcoxon rank-sum tests, chi-squared tests, and Fisher’s exact tests were used to determine significance of difference between data sets at a predetermined level of significance set to p

With the emergence of social media platforms, new bibliometric profiles measuring impact and exposure of scientific research online have been introduced as an alternative to traditional bibliometric outcomes. The objective of this article is to evaluate relationships between Altmetric scores, journal impact factor, and citation counts among the surgical literature.We analyzed the top 10 highest cited articles for the 10 general surgery journals with the highest impact factors for 2013 and 2016 by noting citation counts and Altmetric scores for each article. We also identified the journal impact factor and age of journal associated Twitter accounts. Variables were assessed for correlation using Pearson's correlation testing via Microsoft Excel.A total of 240 articles were analyzed. For 2013, Altmetrics score analysis demonstrated a significant, positive correlation with citation number (r = 0.462, P 0.0001) and journal impact factor (r = 0.439, P 0.0001). The 2016 cohort also demonstrated significant, positive correlations between Altmetric scores and citation count after the removal of one outlier (r = 0.182, P = 0.047) and journal impact factor when considering all articles (r = 0.425, P 0.0001). From 2013 to 2016, the total number of citations for all articles decreased from 11,027 to 7661, but cumulative Altmetric scores increased from 1078 to 4782. Age of creation for a journal's Twitter account did not significantly affect Altmetric score or traditional bibliometric measures in either 2013 (r = 0.370, P = 0.293) or 2016 (r = 0.441, P = 0.202).Altmetric scores, while significantly associated with citation count in the surgical literature, should not necessarily be used as a surrogate marker for evaluating research performance, impact, or exposure. It is possible, however, that as the use of social media for distributing and sharing scientific research continues to expand, that exposure on such platforms could impact future interest or studies.

The unique properties of single-walled carbon nanotubes (SWCNTs) have made them interesting candidates for applications in biomedicine. There are diverse chemical groups that can be attached to SWCNTs in order for these tiny tubes to gain various functionalities, for example, water solubility. Due to the availability of these &ldquo, functionalization&rdquo, approaches, SWCNTs are seen as agents for a potential anti-cancer therapy. In this context, we tested different chemically-functionalized forms of SWCNTs to determine which modifications make them better combatants against glioblastoma (astrocytoma grade IV), the deadliest brain cancer. We investigated the effects that two types of water soluble SWCNTs, functionalized with polyethylene glycol (SWCNT-PEG) or tetrahydrofurfuryl-terminated polyethylene glycol (SWCNT-PEG-THFF), have on the morphology and vitality, that is, cell adhesion, proliferation and death rate, of the D54MG human glioblastoma cells in culture. We found that SWCNT-PEG-THFF solute, when added to culture media, makes D54MG cells less round (measured as a significant decrease, by ~23%, in the form factor). This morphological change was induced by the PEG-THFF functional group, but not the SWCNT backbone itself. We also found that SWCNT-PEG-THFF solute reduces the proliferation rate of D54MG cells while increasing the rate of cell death. The functional groups PEG and PEG-THFF, on the other hand, reduce the cell death rate of D54MG human glioma cells. These data indicate that the process of functionalization of SWCNTs for potential use as glioma therapeutics may affect their biological effects.

The unique two-dimensional structure and outstanding electronic, thermal, and mechanical properties of graphene have attracted the interest of scientists and engineers from various fields. The first step in translating the excellent properties of graphene into practical applications is the preparation of large area, continuous graphene films. Chemical vapour deposition (CVD) graphene has received increasing attention because it provides access to large-area, uniform, and continuous films of high quality. However, current CVD synthetic techniques utilize metal substrates (Cu or Ni) to catalyse the growth of graphene and post-growth transfer of the graphene film to a substrate of interest is critical for most applications such as electronics, photonics, and spintronics. Here we discuss recent advances in the transfer of as-grown CVD graphene to target substrates. The methods that afford CVD graphene on a target substrate are summarized under three categories: transfer with a support layer, transfer without a support layer, and direct growth on target substrates. At present the first two groups dominate the field and research efforts are directed towards refining the choice of the support layer. The support layer plays a vital role in the transfer process because it has direct contact with the atomically thin graphene surface, affecting its properties and determining the quality of the transferred graphene.

CVD graphene has attracted a great deal of interest from both academia and industry. The strong motivation to commercialize high quality CVD graphene films and related devices has been restricted by the lack of a cheap, efficient, clean and reliable graphene transfer process. In this article, we report a novel graphene transfer technique which provides a route to high-throughput, reliable and economical transfer of graphene without introducing large cracks and residue contamination from polymers, such as PMMA or magnetic impurities. The transferred graphene was thoroughly characterized with Raman spectroscopy, Atomic Force Microscopy, and X-ray photoelectron spectroscopy. Fabricated large area graphene-based field effect transistors exhibited high mobilities, which were about 2 times higher than those for devices prepared with graphene transferred by the conventional wet transfer method. This new graphene transfer technique has the potential to expedite the large scale industrial utilization of CVD graphene in electronics, spintronics, catalysis and energy storage.

We report the synthesis of vulcanized polyisoprene (SPIP) nanowires and an investigation of the electrochemical lithiation mechanism of the covalently bonded sulfur bridges in SPIP. Electrochemical analysis demonstrates that the sulfur chains in SPIP have distinct electrochemical signatures from those that are characteristic of bulk elemental sulfur. The cyclic voltammetry and galvanostatic cycling data show a distinct multistep charge-transfer process and solid-state lithium–sulfur reaction behavior, and it is clear that this new material provides a promising basis for the development of cathodes for rechargeable batteries. Chemical changes due to the lithiation process are studied using Raman and X-ray photoelectron spectroscopy, on the basis of which new lithiation mechanisms of covalently bonded sulfur are proposed.

The Hammond Postulate and the Leffler analysis have provided a cornerstone in the understanding of reaction processes in organic chemistry for over 60 years, yet quantitative applications of these methodologies over the range of reactions envisaged in the original works remain elusive. In the present paper, we analyze a series of SN2 reactions in three solvents that lead to endothermic and exothermic reaction processes, and we show that within the hybridization reaction coordinate the SN2 reaction is fully consistent with both treatments. We give new presentations of the reaction energies as a function of reaction progress, which allow the generation of unified reaction coordinate diagrams that show a linear relationship between the hybridization metric of reaction progress and the relative energies of the stationary points on the potential surface as a function of structure and solvent as originally envisaged by Leffler and Hammond.

The formation of bis-hexahapto bonds between graphitic surfaces can electronically interconnect the surfaces of carbon materials containing the polybenzenoid ring system and increase the conductivity without introducing a strong perturbation to the in-plane electronic structure. In this paper, we report the use of organometallic chemistry to interconnect the surfaces of small scale graphene nanoplatelets by using a variety of metals and photochemically activated organometallic reagents.

We consider the covalent chemistry of the carbon allotropes with an emphasis on the newest member—graphene. We focus on the effect of such chemistry on the geometric and electronic structure of the functionalized materials and the way in which the conjugation is modified by such processes. We conclude that there are two limiting cases: (a) Conventional addition chemistry leading to the formation of σ-bonds to the graphitic surface in which there is full rehybridization of the derivatized carbon atoms from sp 2 to sp 3 ; thus these carbon atoms are effectively removed from conjugation and from the electronic band structure (referred to as destructive rehybridization). (b) Covalent chemisorption with formation of an organometallic hexahapto-metal bond that largely preserves the graphitic band structure (constructive rehybridization) and accompanies the formation of bis-hexahapto-metal bonds such as those in (η 6 -SWNT)Cr(η 6 -SWNT) which serve to interconnect adjacent graphitic surfaces and significantly reduces the internanotube junction resistance in SWNT networks. The formation of η 2 di-hapto bonds represent an intermediate case of covalent chemistry and is known to be important in carbon nanotubes and particularly the fullerenes but this situation has been treated in detail in previous publications.

Single-walled carbon nanotube (SWNT) thin films provide a unique platform for the development of electronic and photonic devices because they combine the advantages of the outstanding physical properties of individual SWNTs with the capabilities of large area thin film manufacturing and patterning technologies. Flexible SWNT thin film based field-effect transistors, sensors, detectors, photovoltaic cells, and light emitting diodes have been already demonstrated, and SWNT thin film transparent, conductive coatings for large area displays and smart windows are under development. While chirally pure SWNTs are not yet commercially available, the marketing of semiconducting (SC) and metallic (MT) SWNTs has facilitated progress toward applications by making available materials of consistent electronic structure. Nevertheless the electrical transport properties of networks of separated SWNTs are inferior to those of individual SWNTs. In particular, for semiconducting SWNTs, which are the subject of this Account, the electrical transport drastically differs from the behavior of traditional semiconductors: for example, the bandgap of germanium (E = 0.66 eV) roughly matches that of individual SC-SWNTs of diameter 1.5 nm, but in the range 300-100 K, the intrinsic carrier concentration in Ge decreases by more than 10 orders of magnitude while the conductivity of a typical SC-SWNT network decreases by less than a factor of 4. Clearly this weak modulation of the conductivity hinders the application of SC-SWNT films as field effect transistors and photodetectors, and it is the purpose of this Account to analyze the mechanism of the electrical transport leading to the unusually weak temperature dependence of the electrical conductivity of such networks. Extrinsic factors such as the contribution of residual amounts of MT-SWNTs arising from incomplete separation and doping of SWNTs are evaluated. However, the observed temperature dependence of the conductivity indicates the presence of midgap electronic states in the semiconducting SWNTs, which provide a source of low-energy excitations, which can contribute to hopping conductance along the nanotubes following fluctuation induced tunneling across the internanotube junctions, which together dominate the low temperature transport and limit the resistivity of the films. At high temperatures, the intrinsic carriers thermally activated across the bandgap as in a traditional semiconductor became available for band transport. The midgap states pin the Fermi level to the middle of the bandgap, and their origin is ascribed to defects in the SWNT walls. The presence of such midgap states has been reported in connection with scanning tunneling spectroscopy experiments, Coulomb blockade observations in low temperature electrical measurements, selective electrochemical deposition imaging, tip-enhanced Raman spectroscopy, high resolution photocurrent spectroscopy, and the modeling of the electronic density of states associated with various defects. Midgap states are present in conventional semiconductors, but what is unusual in the present context is the extent of their contribution to the electrical transport in networks of semiconducting SWNTs. In this Account, we sharpen the focus on the midgap states in SC-SWNTs, their effect on the electronic properties of SC-SWNT networks, and the importance of these effects on efforts to develop electronic and photonic applications of SC-SWNTs.

α-Arylated carbonyl derivatives are important structural motifs in many natural products and pharmaceutically active compounds. Although arylation of simple monocarbonyl compounds is a well-established methodology, metal-catalyzed arylation of β-dicarbonyl derivatives is significantly more challenging. The ability of β-dicarbonyl anions to bind to palladium in a κ2-O,O mode, rather than the κ1-C-bound mode required for bond formation, often results in the deactivation of catalyst systems. The C-bound form of the enolate can be favored through the use of sterically demanding ligands. Herein, we report that the sterically demanding di-tert-butylneopentylphosphine (DTBNpP) ligand in combination with Pd(dba)2 provides an effective catalyst for the coupling of aryl bromides and chlorides with diethyl malonate. The Pd/DTBNpP system also catalyzes the coupling of aryl bromides with ethyl cyanoacetate.

We spectroscopically analyze the effect of e-beam deposition of lanthanide metals on the electronic structure and conductivities of films of semiconducting (SC) single-walled carbon nanotubes (SWNTs) in high vacuum. We employ near-infrared and Raman spectroscopy to interpret the changes in the electronic structure of SWNTs on exposure to small amounts of the lanthanides (Ln = Sm, Eu, Gd, Dy, Ho, Yb), based on the behavior of the reference metals (M = Li, Cr) which are taken to exemplify ionic and covalent bonding, respectively. The analysis shows that while the lanthanides are more electropositive than the transition metals, in most cases they exhibit similar conductivity behavior which we interpret in terms of the formation of covalent bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = La, Nd, Gd, Dy, Ho]. However, only M = Eu, Sm, Yb show the continually increasing conductivity characteristic of Li, and this supports our contention that these metals provide the first examples of mixed covalent-ionic bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = Sm, Eu, Yb].

The solution phase reactions of single-walled carbon nanotubes (SWNTs) with Cr(CO)6 and benzene-Cr(CO)3 can lead to the formation of small chromium clusters. The cluster size can be varied from less than 1 nm to about 4 nm by increasing the reaction time. TEM images suggest that the clusters are deposited predominantly on the exterior walls of the nanotubes. TGA analysis was used to obtain the Cr content and carbon to chromium ratio in the Cr-complexed SWNTs. It is suggested that the carbon nanotube benzenoid structure templates the condensation of chromium atoms and facilitates the loss of carbon monoxide leading to well defined metal clusters.

The electrical conductivity of single-walled carbon nanotube (SWNT) networks is strongly enhanced by the high vacuum e-beam deposition of transition metals. In the present communication we demonstrate that it is possible to accomplish the same chemical functionalization reactions at room temperature beginning with simple organometallic precursors. We show that the photochemically induced reactions of solutions of Cr(CO)6, Cr(η6-benzene)(CO)3, and Cr(η6-benzene)2 with thin films of semiconducting, metallic and non-separated SWNT films all lead to strongly enhanced conductivities which produce consistent results for each SWNT type among the three organometallic reagents. We conclude that all three of these reactions lead to the generation of covalent (η6-SWNT)Cr(η6-SWNT) interconnects which provide conducting pathways in the SWNT films and our results broaden the applicability of the transition metal bis-hexahapto-bond as an electronically conjugating linkage between graphene surfaces.

Polymorphism is an important issue for the application of organic semiconductors in field-effect transistors due to the dependence of device performance on crystal packing. Recently an organic semiconductor, 6,13-dichloropentacene (DCP), was shown to give a field-effect mobility as high as 9 cm2 V−1 s−1 when crystallized in the form of microribbons obtained by physical vapor transport (PVT), in contrast with the much lower mobilities found in crystals grown from solution. In the present manuscript we show that the crystals grown in the vapor phase are a polymorph of the structure reported for the crystals grown from solution. Both polymorphs show a π-stacking motif but differ in the interplanar distances and the displacement of the molecules along the long axes of the molecules. The DCP PVT structure compares favorably to that of rubrene, but DCP shows a much lower mobility. Band structure calculations show that the rubrene crystal exhibits greater band dispersion than DCP even though the long-axis displacement in rubrene is much greater. We conclude that the transport properties cannot be inferred simply by the magnitude of the intrastack long-axis displacement, but requires a consideration of the relative location of the HOMO/LUMO coefficients of the neighboring molecules in the stack.

Ultraviolet (UV) photodetectors based on heterojunctions of conventional (Ge, Si, and GaAs) and wide bandgap semiconductors have been recently demonstrated, but achieving high UV sensitivity and visible-blind photodetection still remains a challenge. Here, we utilized a semitransparent film of p-type semiconducting single-walled carbon nanotubes (SC-SWNTs) with an energy gap of 0.68 ± 0.07 eV in combination with a molecular beam epitaxy grown n-ZnO layer to build a vertical p-SC-SWNT/n-ZnO heterojunction-based UV photodetector. The resulting device shows a current rectification ratio of 103, a current photoresponsivity up to 400 A/W in the UV spectral range from 370 to 230 nm, and a low dark current. The detector is practically visible-blind with the UV-to-visible photoresponsivity ratio of 105 due to extremely short photocarrier lifetimes in the one-dimensional SWNTs because of strong electron–phonon interactions leading to exciton formation. In this vertical configuration, UV radiation penetrates the to...

This paper reports the successful fabrication of phenyl hydrazine chemical sensor based on CoAl07Fe13O4 ferrite nanoparticles. The CoAl07Fe13O4 ferrite nanoparticles were synthesized by simple and facile co-precipitation method and characterized in terms of their morphological, structural, compositional and electrical properties. The detailed characterizations confirmed that the prepared ferrite nanoparticles are grown in nanostructure, possessing CoAl07Fe13O4 composition and spinel structure of cubic phase. The fabricated phenyl hydrazine chemical sensor based on CoAl07Fe13O4 nanoparticles exhibited a high and reproducible sensitivity of ∼32342 Am M −1 cm −2 with the low experimental detection limit of 0.625 mM in a short response time of ∼100 s. The fabricated sensor shows a linear dynamic range from 0.625 mM to 10 mM. This presented work demonstrates that simply prepared CoAl07Fe13O4 ferrite nanoparticles are efficient electron mediators for the fabrication of robust and reliable chemical sensors for the detection of hazardous chemicals.

With the advent of many different forms of graphene (in addition to the long standing interest in fullerenes and carbon nanotubes), the characterization of carbon materials and their degree of conjugation is a particularly important topic in carbon science. We report the application of absorption spectroscopy and conductivity measurements to graphene derivatives and related carbon materials. Reduced graphene oxide (RGO) has been widely studied as a promising material for graphene applications because of its processability, and the same considerations apply to graphene functionalized with octadecylamine (ODA). This study utilizes a direct chemical modification of GO with ODA in the presence of dicyclohexylcarbodiimide to partially regenerate the graphene π-conjugation while producing a material (ODA-G) with excellent solubility in organic solvents. We show that the ODA-G exhibits optical absorptions, which are much stronger than those of GO, and comparable to liquid phase exfoliated graphene and reduced graphene oxide; the optical analysis is unified by the development of an analytical relationship between solid state absorption coefficients and solution state extinction coefficients, which allows the direct comparison of the electronic absorption spectroscopy of films and solutions of carbon materials. We further benchmark the regeneration of the graphenic structure in ODA-G with electrical conductivity measurements.

Porphyrins due to their unique and interesting physicochemical properties have been widely investigated as functional materials for chemical sensor fabrication. However, their poor conductivity is a major limitation toward the realization of porphyrin-based field-effect transistor/chemiresistor sensor. The issue of conductivity can be overcome by exploiting the excellent electrical property of single-walled carbon nanotubes (SWNTs) to make a SWNTs-based hybrid device in which SWNTs would act as a transducer and porphyrin as a sensory layer. The present attempt was to fabricate a SWNTs–poly(tetraphenylporphyrin) hybrid through electrochemical route and to evaluate its potential as a low-power chemiresistor sensor for sensing acetone vapor as a model for volatile organic compounds. Functionalization of SWNTs with porphyrin polymer by the electrochemical method resulted in a fuller coverage of SWNTs surface compared to a partial coverage by adsorption and thereby higher sensitivity. SWNTs were coated with po...

We report the formation of chromium clusters on the outer walls of single-walled carbon nanotubes (SWNTs). The clusters were obtained by reacting purified SWNTs with chromium hexacarbonyl in dibutyl ether at 100 degrees C. The functionalized SWNTs were characterized by thermogravimetic analysis, XPS, and high-resolution TEM. The curvature of the SWNTs and the high mobility of the chromium moieties on graphitic surfaces allow the growth of the metal clusters and we propose a mechanism for their formation.

In this Perspective, we present an overview of recent fundamental studies on the nature of the interaction between individual metal atoms and metal clusters and the conjugated surfaces of graphene and carbon nanotube with a particular focus on the electronic structure and chemical bonding at the metal–graphene interface. We discuss the relevance of organometallic complexes of graphitic materials to the development of a fundamental understanding of these interactions and their application in atomtronics as atomic interconnects, high mobility organometallic transistor devices, high-frequency electronic devices, organometallic catalysis (hydrogen fuel generation by photocatalytic water splitting, fuel cells, hydrogenation), spintronics, memory devices, and the next generation energy devices. We touch on chemical vapor deposition (CVD) graphene grown on metals, the reactivity of its surface, and its use as a template for asymmetric graphene functionalization chemistry (ultrathin Janus discs). We highlight som...

We report the synthesis and properties of a series of spiro-bis(3,4,6,7-tetrachalcogenide-substituted-phenalenyl)boron salts and two of the corresponding tetrathioalkyl-substituted spiro-bis(phenalenyl)boron radicals [tetrathiomethyl (10) and tetrathioethyl (11)] in which all of the active positions of the phenalenyl (PLY) nucleus are functionalized. In the solid state, radicals 10 and 11 exist as a weak π-dimers due to the steric congestion of the thioalkyl groups in the superimposed PLY units. As a result, the spins are localized in the isolated (nonsuperimposed) PLY rings, and the structure, magnetic susceptibility measurements, and band structure calculations confirm that these PLY units are unable to undergo strong intermolecular interaction as a result of the orientation of the thioalkyl groups.