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A novel class of π-extended 11-ring-fused linear thienoacenes (BBDTB-H, BBDTB-TIPS, and BBDTB-Br) with four thieno[3,2-b;4,5-b′]dithiophenes and three benzene rings were synthesized and fully characterized.

In last decades, open-shell organic materials have attracted scientists’ great attention for their new chemical and physical properties, as well as their possible applications in new generation of organic light-emitting diodes (OLEDs), organic field effect transistors (OFETs), organic spintronics and photonics, and so on. In this review, we summarize the recent progress of design and synthesis of open-shell organic magnetic materials. Especially, we will focus on their aggregated states in OFETs, organic conductors and luminescent devices and photoinduced radical materials, with the aim to provide some clue for the further development of novel open-shell organic magnetic materials.

Fully conjugated macrocycles containing benzenoid rings rarely show global aromaticity/antiaromaticity. Herein, we report an annulene-like macrocycle CBTT and its S,S-dioxidized macrocycle DOCBTT with alternative quinoidal thiophene/1,1-dioxide thiophene and triphenyl amine moieties. They both showed temperature-dependent intramolecular dynamics and global antiaromatic character with 32π electrons at low temperature. However, CBTT and DOCBTT have different conjugated pathways.

Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure, but their synthesis is very challenging. Herein, we report a facile synthetic strategy prima...

Incorporation of a non-hexagonal ring into a nanographene framework can lead to new electronic properties. During the attempted synthesis of naphthalene-bridged double [6]helicene and heptagon-containing nanographene by the Scholl reaction, an unexpected azulene-embedded nanographene and its triflyloxylated product were obtained, as confirmed by X-ray crystallographic analysis and 2D NMR spectroscopy. A 5/7/7/5 ring-fused substructure containing two formal azulene units is formed, but only one of them shows an azulene-like electronic structure. The formation of this unique structure is explained by arenium ion mediated 1,2-phenyl migration and a naphthalene to azulene rearrangement reaction according to an in-silico study. This report represents the first experimental example of the thermodynamically unfavorable naphthalene to azulene rearrangement and may lead to new azulene-based molecular materials.

π-Conjugated macrocycles containing all-benzenoid rings usually show local aromaticity, but reported herein is the macrocycle CBQT, containing alternating para-quinodimethane and triphenylamine units displaying annulene-like anti-aromaticity at low temperatures as a result of structural rigidity and participation of the bridging nitrogen atoms in π-conjugation. It was easily synthesized by intermolecular Friedel-Crafts alkylation followed by oxidative dehydrogenation. X-ray crystallographic structures of CBQT, as well as those of its dication, trication, and tetracation were obtained. The dication and tetracation exhibited global aromaticity and antiaromaticity, respectively, as confirmed by NMR measurements and theoretical calculations. Both the dication and tetracation possess open-shell singlet ground states, with a small singlet-triplet gap.

Linear quinodimethane-embedded acene analogue 9L was synthesized, and its quinoidal structure was confirmed by X-ray crystallographic analysis. The multiple oxidation states of 9L could be achieved. Its dication is a triplet diradical, and its tetracation can be regarded as the isoelectronic structure of the nonacene, which was validated by experiments and theoretical calculations.

Photochemistry based on acenes and their derivatives is one of the emerging research areas in the field of polycyclic aromatic hydrocarbons (PAHs). However, due to the increased reactivity of larger acenes towards light and singlet oxygen, it is difficult to precisely control their photochemical reactions. Therefore, the unexpected reactivity of acene-based molecules brings about two challenging topics: how to design stable acenes and how to utilize the photochemistry to design new acene-based functional materials. In this review, we first focus on the mechanism of photochemistry of acenes to theoretically understand how these reactions could have happened. Next, we will give a summary on both acene-based photocyclization and photooxidation reactions.

Creating atomically precise quantum architectures with high digital fidelity and desired quantum states is an important goal in a new era of quantum technology. The strategy of creating these quantum nanostructures mainly relies on atom-by-atom, molecule-by-molecule manipulation or molecular assembly through non-covalent interactions, which thus lack sufficient chemical robustness required for on-chip quantum device operation at elevated temperature. Here, we report a bottom-up synthesis of covalently linked organic quantum corrals (OQCs) with atomic precision to induce the formation of topology-controlled quantum resonance states, arising from a collective interference of scattered electron waves inside the quantum nanocavities. Individual OQCs host a series of atomic orbital-like resonance states whose orbital hybridization into artificial homo-diatomic and hetero-diatomic molecular-like resonance states can be constructed in Cassini oval-shaped OQCs with desired topologies corroborated by joint ab initio and analytic calculations. Our studies open up a new avenue to fabricate covalently linked large-sized OQCs with atomic precision to engineer desired quantum states with high chemical robustness and digital fidelity for future practical applications., Creating atomically-precise quantum architectures with high digital fidelity and desired quantum states is an important goal for quantum technology applications. Here the authors devise an on-surface synthetic protocol to construct atomically-precise covalently linked organic quantum corrals with the formation of a series of new quantum resonance states.

A tetraindeno-fused bis(anthraoxa)quinodimethane RBR with nine consecutively fused six-membered rings in a row was synthesized. Its structure was confirmed by X-ray crystallographic analysis and NMR measurement. Compared with an unfused analogue ABA, the indeno fusion onto the zigzag edges not only enhanced the photostability but also dramatically tuned the electronic properties. Due to the existence of two rubicene units, RBR can also be readily reduced to form a radical anion and dianion.

Synthesis of a carbon nanobelt (CNB) is a very challenging task in organic chemistry. Herein, we report the successful synthesis of an octabenzo[12]cyclacene based CNB (6), which can be regarded as a sidewall fragment of a (12,0) carbon nanotube. The key intermediate compound, a tetraepoxy nanobelt (5), was first synthesized by Diels-Alder reaction, and subsequent reductive aromatization gave the fully conjugated CNB 6. X-ray crystallographic analysis unambiguously confirmed the belt-shaped structure of 6. 1 H NMR spectrum and theoretical calculations (ACID, NICS, and 2D/3D ICSS) revealed localized aromaticity and stronger shielding chemical environment in the inner region of the belt. The optical properties (absorption and emission) of 6 were studied and correlated to its electronic structure. Strain analysis indicates that the phenyl substituents at the zigzag edges are crucial to the successful synthesis of 6. This report presents a new strategy towards highly strained CNBs.

The synthesis of peri-fused acenes (peri-acenes) with two or more rows is challenging due to their intrinsic open-shell diradical character. Herein, we report the isolation of a derivative (4) of [4,3]peri-acene in crystalline form. The parent [4,3]peri-acene, containing three rows of tetracene, has a large diradical character (y0 =94.8 %) originating from aromatic stabilization. Due to kinetic blocking, 4 showed a reasonable stability with a half-life time of ≈157 h under ambient conditions. Its structure was determined by X-ray crystallographic analysis, and bond-length analysis revealed eight localized Clar's sextets. 4 exhibited an open-shell singlet ground state with a narrow electrochemical energy gap (1.13 eV) and a small singlet-triplet energy gap (-0.57 kcal mol-1 from SQUID measurements). Its electronic properties are compared with previously reported peri-tetracene and teranthene derivatives.

We report the challenging synthesis of two very long bis(anthraoxa)quinodimethanes with nine (ABA) and ten (ANA) consecutively fused six-membered rings. The former is stable with negligible diradical character, while the latter with a moderate diradical character (y0 = 25.0%) is reactive and an unexpected trifluoroacetic substituted product (ANA-TFA) was isolated. X-ray crystallographic analysis revealed a planar backbone with a typical quinoidal character for both. Their dications can be regarded as the isoelectronic structures of the respective nonacene and decacene. The dication ABA2+ and dianion ABA2– are open-shell singlet diradicaloids, while the longer dication ANA-TFA2+ and dianion ANA2– have closed-shell ground state, which can be explained by the different intramolecular Coulomb interactions. Both dianions have a bent backbone and can be considered as an isoelectronic structure of the tetraanion of nonacene and decacene, respectively.

Higher order acenes (i.e., acenes longer than pentacene) and extended zethrenes (i.e., zethrenes longer than zethrene) are theoretically predicted to have an open-shell singlet ground state, and the radical character is supposed to increase with extension of molecular size. The increasing radical character makes the synthesis of long zethrenes and acenes very challenging, and so far, the longest reported zethrene and acene derivatives are octazethrene and nonacene, respectively. In addition, there is a lack of fundamental understanding of the differences between these two closely related open-shell singlet systems. In this work, we report the first synthesis of a challenging nonazethrene derivative, HR-NZ, and its full structural and physical characterizations including variable temperature NMR, ESR, SQUID, UV-vis-NIR absorption and electrochemical measurements. Compound HR-NZ has an open-shell singlet ground state with a moderate diradical character (y0 = 0.48 based on UCAM-B3LYP calculation) and a small singlet-triplet gap (ΔES-T = -5.2 kcal/mol based on SQUID data), thus showing magnetic activity at room temperature. It also shows amphoteric redox behavior, with a small electrochemical energy gap (1.33 eV). Its electronic structure and physical properties are compared with those of Anthony's nonacene derivative JA-NA and other zethrene derivatives. A more general comparison between higher order acenes and extended zethrenes was also conducted on the basis of ab initio electronic structure calculations, and it was found that zethrenes and acenes have very different spatial localization of the unpaired electrons. As a result, a faster decrease of singlet-triplet energy gap and a faster increase of radical character with increase of the number of benzenoid rings were observed in zethrene series. Our studies reveal that spatial localization of the frontier molecular orbitals play a very important role on the nature of radical character as well as the excitation energy.

Acene-based materials have promising applications for organic electronics but the major constrain comes from their poor stability. Herein a new strategy to stabilize reactive acenes, by fusion of an anti-aromatic pentalene unit onto the zigzag edges of two acene units to form a Z-shaped acene dimer, is introduced. The Z-shaped acene dimers are extremely stable and show a small energy gap resulting from intramolecular donor-acceptor interactions. X-ray crystallographic analysis revealed their unique geometry and one-dimensional slip-stack columnar structure. Besides optical and electrochemical characterizations, solution-processed field-effect transistors were also fabricated.

Three new N-annulated perylene (NP) substituted porphyrin dyes WW-7–WW-9 with different linking modes and accepting groups were synthesized and applied in Co(II)/(III) based dye sensitized solar cells (DSCs). The bay-linked porphyrins WW-7 and WW-8 exhibited moderate power conversion efficiency (PCE = 4.4% and 4.8%, respectively), while the peri-linked porphyrin dye WW-9 showed a PCE up to 9.2% which is slightly lower than that of our reference dye WW-6. Detailed physical measurements (optical and electrochemical), DFT calculations, and photovoltaic characterizations were performed to understand how the structural changes affect their light-harvesting ability, molecular orbital profile, energy level alignment, and eventually the photovoltaic performance. It turned out that the lower efficiencies of the cells based on WW-7 and WW-8 could be ascribed to the weak π-conjugation between the bay-substituted NP and phenylethynyl substituted porphyrin unit. The introduction of a benzothiadiazole acceptor at the anchoring group has induced a significant red shift of the IPCE action spectra of WW-8 and WW-9, by about 90 nm and 50 nm as compared to that of WW-7 and WW-6, respectively. However, less efficient electron injection was observed. Our studies gave some insight into the important role of electronic interactions between different components when one designs a dye for high-efficiency DSCs.

Solution processible organic semiconductors have attracted great attention in recent years due to their applications in printable electronics, such as organic thin-film transistor (OTFT). This type of device requires semiconductors characterized by low reorganization energies and strong intermolecular electronic interaction. Phthalocyanines are 18 π -electron disc-like aromatic macrocycles with two-dimensional (2D) π -electron delocalization over the whole molecule, and are featured with low reorganization energies and close π - π stacking. Moreover, tight 2D cofacial π - π stacking, which is beneficial for charge transport in the channel of OTFTs, can be realized by incorporating axially substituted metals or large metals in the core of phthalocyanines. Introducing alkyl substituents can endow phthalocyanines good solubility in organic solvents. However, the number and positions of alkyl substituents have great influence on the packing structures thereby OTFT performance of phthalocyanines. In the current paper, four dioctyl substituted vanadyl phthalocyanines, i.e. 2,3-dioctyl vanadyl phthalocyanine (2,3-C8OVPc), 2,16(17)-dioctyl vanadyl phthalocyanine ( dp - C8OVPc), 1,15-dioctyl vanadyl phthalocyanine (1,15-C8OVPc) and 1,18-dioctyl vanadyl phthalocyanine ( dp -C8OVPc), were synthesized, and the effect of the positions of octyl groups on their photophysical properties, OTFT performance was studied in detail. All four compounds are soluble in organic solvents such as chloroform and exhibit excellent thermal stability with the decomposition temperature ( T d) beyond 400°C. In dilute solution, the positions of octyl groups have negligible influence on their absorption spectra and frontier molecular orbital energy levels. Their absorption maxima ( λ max) are all at ca. 700 nm and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels are - 5.2 and - 3.8 eV, respectively. From solution to film, their absorption spectra exhibited a remarkable bathochromic shift. In film state, four compounds all can form ordered thin films, in which they arrange in an edge-on way. Bottom gate and top contact OTFTs based on thermally annealed films of these four compounds were fabricated via solution spin-casting. All compounds showed p-type transport behavior with field-effect mobility above 0.1 cm2/(V s) 2,3-C8OVPc displayed the best OTFT device performance. A mobility of 0.19 cm2/(V s) has been demonstrated when the films were annealed at 150°C.

Two BODIPY-substituted anthroxyl radicals were investigated. The one with two ethyl substituents (2Et-BO-An-O) is sensitive to air and silica gel due to the lack of sufficient kinetic blocking, while another one with four methyl substituents (4Me-BO-An-O) shows high stability. The structure of the latter was fully characterized by X-ray crystallographic analysis and electron–spin resonance spectra. 4Me-BO-An-O was subjected to react with various reactive oxygen/nitrogen species (ROS/RNS) and selective fluorescence turn-on detection of a hydroxyl radical was achieved, validating the concept of “using stable radicals to detect ROS/RNS”.

Commercial Li4Ti5O12 is modified by AlF3 with the purpose of suppressing the gas generation of Li4Ti5O12 anode battery. The prepared AlF3-modified Li4Ti5O12 is characterized by a variety of means such as X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The results indicate that only part of Al3+ and F− have co-doped into the bulk phase of Li4Ti5O12 particles, while the rest of the Al3+ and F− remain on the surface of the Li4Ti5O12 particles to form an AlF3 coating layer. The AlF3 coating layer on the surface of AlF3-modified Li4Ti5O12 is very effective in suppressing the gas generation of Li4Ti5O12 anode battery. AlF3 modification is a simple yet very effective strategy, which can both improve the high-rate charge/discharge performance of Li4Ti5O12 and suppress the gassing behavior of Li4Ti5O12 anode battery.

Extended bis(benzothia)quinodimethanes and their dications were synthesized as stable species. The neutral compounds mainly have a quinoidal structure in the ground state but show increased diradical character with extension of the central quinodimethane unit. The dications exhibit similar electronic absorption spectra, NMR spectra, NICS values, and diatropic ring currents to their aromatic all-carbon acene analogues and thus can be regarded as genuine isoelectronic structures of pentacene, hexacene, and heptacene, respectively. Our research gave some insights into the design and synthesis of stable longer acene analogues.

Four structural isomers of non-peripheral tetrahexyl-substituted vanadyl phthalocyanine can be easily separated using common laboratory column chromatography on a gram scale. The most abundant isomer, 1,8,18,22-tetrahexyl vanadyl phthalocyanine (I-3), adopts intermolecular 2D cofacial pi-pi stacking and exhibits a field-effect mobility of up to 0.13 cm(2) V(-1) s(-1).

Two series of oligothiophenes (OThs), NaTn and TNTn (n = 2-6 represents the number of thiophene rings), end-capped with naphthyl and thionaphthyl units have been synthesized by means of Stille coupling. Their thermal properties, optical properties, single crystal structures, and organic field-effect transistor performance have been characterized. All oligomers display great thermal stability and crystallinity. ne crystallographic structures of NaT2, NaT3, TNT2, and TNT3 have been determined. The crystals of NaT2 and NaT3 are monoclinic with space group P2(1)/C, while those of TNT2 and TNT3 are triclinic and orthorhombic with space groups P-1(-) and P2(1)2(1)2(1), respectively. All oligomers adopt the well-known herringbone packing-mode in crystals with packing parameters dependent on the structure of the end-capping units and the number of thiophene rings. The shorter intermolecular distance in NaT3 compared to NaT2 indicates that the intermolecular interaction principally increases with increasing molecular length. X-ray diffraction and atomic force microscopy (AFM) characterization indicate that the NaTn oligomers can form films with better morphology and high molecular order than TNTn oligomers with the same number of thiophene rings. The NaTn oligomers exhibit mobilities that are much higher than those for TNTn oligomers (0.028-0.39 cm(2) V-1 s(-1) versus 0.010-0.055 cm(2) V-1 s(-1), respectively).

Most plastic processing set points are variables that need to be defined for each sample point of the cycle. However, in the absence of on-line measures of part quality, the set points cannot be defined by feedback and need to be prescribed a priori for the entire cycle. In conventional practice, the shape of each set-point profile is defined either heuristically, according to qualitative experience, or mechanistically, to enforce a predefined trajectory for a simulated internal process state that is used as a surrogate measure of part quality (e.g., the velocity profile defined to dictate a constant melt front velocity). The purpose of this study is twofold: (i) to evaluate the efficacy of using a single internal state as the surrogate of part quality, and (ii) to explore the feasibility of devising a multivariate profiling approach, where indices of multiple process states act as surrogates of part quality. For this study, an injection-compression molding process used for production of digital video disks was considered as the development domain, and a pseudo-optimal cycle of the process was found by reinforcement learning to provide a basis for evaluating the ideal behavior of the process states. Compared to conventional molding, the results indicate that the asymmetric process capability index, CPK, was increased by ∼50% with velocity profile optimization and to 120% with both velocity profile and pressure profile optimization. Two general conclusions result. First, velocity and pressure profiling provide important degrees of freedom for optimizing process control and maximizing part quality. Second, estimators for unobservable process states, in this case birefringence and warpage, can be used to develop different machine profiles to selectively trade off multiple quality attributes according to user preferences.

A new methodology is developed for optimal infeed control of cylindrical plunge grinding cycles. Unlike conventional cycles having a few sequential stages with discrete infeed rates, the new methodology allows for continuous variation of the infeed rate to further reduce the cycle time. Distinctive characteristics of optimal grinding cycles with variable infeed rates were investigated by applying dynamic programming to a simulation of the grinding cycle. The simulated optimal cycles were found to consist of distinct segments with predominant constraints. This provided the basis for an optimal control policy whereby the infeed rate is determined according to the active constraint at each segment of the cycle. Accordingly, the controller is designed to identify the state of the cycle at each sampling instant from on-line measurements of power and size, and to then compute the infeed rate according to the optimal policy associated with that state. The optimization policy is described in this paper, and the controller design and its implementation are presented in the following paper [1].

This is the second of two papers concerned with on-line optimization of cylindrical plunge grinding cycles with continuously varying infeed control. In the first paper [1], dynamic programming was applied to a simulation of the cylindrical grinding process in order to explore the characteristics of optimal grinding cycles. Optimal cycles were found to consist of distinct segments each with predominant constraints. An optimal control policy was formulated with the infeed rate within each segment determined according to the prevailing constraint. The present paper is concerned with the design of the controller and its implementation. The control system to implement the optimization policy is described together with provisions to enhance robustness to modeling uncertainty and measurement noise. Robustness provisions include model adaptation by parameter estimation from on-line measurements of size and power, and incorporation of safety margins in the optimization process. Problems associated with practical implementation of the control system, stemming from power limitations and wheel wear, are also discussed. The controller performance is demonstrated on an instrumented internal cylindrical grinding machine.

Three types of alkyl-substituted vanadyl phthalocyanines (OVPcs) were synthesized and their organic thin film transistors (OTFTs) were prepared by solution casting with a bottom gate and top contact device geometry. A peripheral octaoctyl-substituted OVPc (OVPc- op -C8) showed the mobility in the order of 10 -5 cm 2 /V•s. Both peripheral and nonperipheral tetraalkyl-substituted OVPcs are a mixture of four isomers, and exhibited the mobility of 10 -4 -10 -2 cm 2 /V•s, depending on the length of the alkyl chains. Four isomers of non-peripheral tetraalkyl-substituted OVPcs can be separated by common lab column chromatography. A mobility of 0.13 cm 2 /V•s has been demonstrated with a pure isomer.

Tetraoctyl-substituted vanadyl phthalocyanine (OVPc4C8) as a new NIR-absorbing discotic liquid crystalline material can form highly ordered thin films with edge-on alignment of the molecules and molecular packing mode identical to that in the phase II of OVPc for solution processed OTFTs with mobility up to 0.017 cm(2) V(-1) s(-1).

This paper considers a two-tier hierarchical heterogeneous wireless sensor network using the concept of clustering. The network has two type of nodes: regular sensor nodes (litenodes or LN) with limited communications, storage, energy, and computation power; and high-end sophisticated nodes (SNs), or clusterheads, with significantly additional resources. The litenodes communicate their data to the SNs and the SNs forward all collected data to a central gateway node called the base station (BS). Our network architecture allows the LNs to reach a SN via multiple hops through other LNs. We investigate the problem of optimally placing a minimum number of sophisticated nodes to handle the traffic generated by the lite nodes, while ensuring that the SNs form a connected network using their wireless links. This placement problem is formulated and solved as multi-constraint optimization problem using well known approaches: Binary Integer Linear Programming (BILP) approach, Greedy approach (GREEDY) and Genetic Algorithm (GA) approach. It was found through simulations that BILP performed best for regular grid topologies, while GA performed better for random LN deployment. Furthermore, the effects of various parameters on the solution are also presented. The paper also proposes a HYBRID approach that uses the solutions provided by GREEDY and/or BILP as the initial solution to the GA. Using HYBRID, results comparable to original GA could be obtained in only 11.46% of the time required for the original GA. � 2008 Springer Science+Business Media, LLC.

This paper proposes a hierarchical two-step localization method for heterogeneous sensor networks. The network consists of three types of nodes: anchor nodes with known locations, a few nodes equipped with both Ultra-Wide Band (UWB) and RF radios, and a large number of sensor nodes called Lite Nodes. By using a hierarchical network architecture and UWB technology, only a small number of anchor nodes are needed. The localization method works in two steps. First, UWB nodes estimate their locations by using the built-in high-precision distance measurement and locations of anchor nodes. Next, Lite Nodes use UWB nodes as references to estimate their locations. The performance of iterative and non-iterative localization methods are compared. It is observed through simulations that iterative method produces much smaller localization error. The effects of UWB node placement and other parameters such as measurement noise, number of anchor nodes, and communication ranges on the resulting localization error are also presented.

Two novel phenanthrene-based conjugated oligomers were synthesized and used as p-channel semiconductors in field-effect transistors; they exhibit high mobility and excellent stability during long-time ambient storage and under UV irradiation.

An approach to approximate interval models by neural networks is proposed. The networks are structured according to the corresponding interval models, which makes them different from the existing interval backpropagation networks. The approach can incorporate analytical knowledge as well as expert's knowledge in the network and can provide transparency to the network. Furthermore, since the networks are linear, they are guaranteed to converge to the minimum. The proposed approach is applied to static interval systems as well as dynamic interval systems. Simulation results indicate that these relative simple interval networks achieve good approximation.