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Four coordination polymers with similar 1D chain motifs exhibited different photosalient behaviors, which can be tuned via monomer preorganization.

Four dinuclear osmium complexes have been constructed for antitumor phototherapy. The most potent Os4 has extremely high photothermal conversion capability under irradiation of an 808 nm low-power laser, targets mitochondria in human melanoma cells without nucleus affinity, and acts as an antitumor photothermal therapy agent

A series of dinuclear Ru

Photodynamic therapy (PDT) using two-photon near-infrared light excitation is a very effective way to avoid the use of short-wavelength ultraviolet or visible light which cannot efficiently penetrate into the biological tissues and is harmful to the healthy cells. Herein, a series of cyclometalated Ir(III) complexes with a structurally simple diimine ligand were designed and the synthetic route and preparation procedure were optimized, so that the complexes could be obtained in apparently higher yield, productivity, and efficiency in comparison to the traditional methods. Their ground state and excited singlet and triplet state properties were studied by spectroscopy and quantum chemistry theoretical calculations to investigate the effect of substituent groups on the photophysical properties of the complexes. The Ir(III) complexes, especially Ir1 and Ir3, showed very low dark toxicities and high phototoxicities under both one-photon and two-photon excitation, indicating their great potential as PDT agents. They were also found to be highly sensitive two-photon mitochondria dyes.

Stereoselective [2 + 2] photocycloaddition provides a desirable synthetic route for target cyclobutane compounds yet remains challenging. In this issue of Chem Catalysis, Weiss and coworkers diligently apply CdSe quantum dots to photocycloaddition reactions and gain nearly quantitative yields of syn-aryl-conjugated vinylcyclobutanes.

Inhibitors of type 1 human immunodeficiency virus (HIV-1) reverse transcriptase are central to anti-HIV therapy. Most of their targets are enzymes, while very few could bind to viral RNA. Here we designed four new polypyridyl Ru(II) complexes, which could bind HIV-1 TAR RNA tightly and selectively by molecular recognition of hydrogen bonds, further stabilize the Ru(II)-RNA bound system by electrostatic attraction, and efficiently inhibit the Moloney murine leukemia virus (M-MuLV) and HIV-1 reverse transcriptase. The polypyridyl Ru(II) complexes also have physical and chemical advantages, including high chemical stability and photostability, sensitive spectroscopic responses to HIV TAR RNA, and low toxicity to normal cells. This work also provides valuable drug design strategies for acquired immune deficiency syndrome (AIDS) and other reverse transcriptase related disease research, such as hepatitis C virus (HCV), Ebola virus (EBOV), influenza A virus, and most recently the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

The photochemical [2+2] cycloaddition of 3,5-bis-(2-(pyridin-4-yl)vinyl)pyridine (bpvp) in the flexible Cd-based metal-alkene frameworks produced different isomeric photoproducts depending on the auxiliary and guest molecules. The bulkiness of the guest molecules influenced the conformation of the ligand, and thus the outcome of the cycloaddition reaction.

Ammonia volatilization emissions constitute the main pathway of nitrogen loss from paddy systems. Present control technologies are based on reducing the amount of nitrogen fertilizer applied. However, ratio of nitrogen loss through ammonia volatilization emissions has not changed, and it has become a bottleneck for promoting nitrogen use efficiency. Therefore, in order to study the effects of film materials on ammonia volatilization emissions, a two-year field plot experiment was carried out with agricultural waste powder and amphipathic molecule materials spread on surface water after nitrogen fertilizer application in paddy system. The results showed that film materials could reduce nitrogen loss through ammonia volatilization by 19%-31% in the paddy season, and this part of nitrogen was accumulated in soil or assimilated by paddy tissue. The ammonium concentration and pH in the surface water and film materials were the major control factors of ammonia volatilization emissions with nitrogen fertilizer application. Moreover, further reductions in ammonia volatilization emissions could be achieved by film materials after reducing nitrogen fertilizer application. Differences in the effect mechanisms of the film materials provide flexible options for practical agricultural production to meet demands.

Coordination polymers [Cd(1,4-bpeb)(L1)] (1), [Zn2(1,4-bpeb)2(L2)2(SO42-)2] (2) and [Cd(1,4-bpeb)(L3)] (H2O) (3) (H2L1, 3-[2-(3-hydroxy-phenoxymethyl)-benzyloxy]-benzoic acid; HL2, 1H-Indazole-3-carboxylic acid; H3L3, benzene-1,2,3-tricarboxylic acid; 1,4-bpeb, 1,4-bis[2-(4-pyridyl)vinyl]benzene have been synthesized under solvothermal conditions. Complexes 1-3 underwent photodimerization in the solid-state to give quantitative yields of single isomeric products. The choice of carboxyl ligands L and metal center determined the arrangement of 1,4-bpeb ligands, which in turn directed the regiochemistry of the final photoproducts. The solid-state network structures of cadmium based 1 and 3 had 1,4-bpeb pairs aligned face-to-face with both C[double bond, length as m-dash]C centres in each ligand at an appropriate distance and alignment for photodimerization to give the corresponding para-[2.2]cyclophane (pCP) exclusively. By contrast, compound 2 possessed dinuclear (ZnSO4)2 metallocycles that positioned the 1,4-bpeb "arms" face-to-face, but with C[double bond, length as m-dash]C centres offset at an appropriate distance for only one pair to undergo [2 + 2] cycloaddition to yield a single stereoisomer of the monocyclobutane photo-product bpbpvpcb. This work highlights crystal engineering design principles that can be used to facilitate regio- and stereospecificity in solid-state transformations.

Six coordination polymers 1–6 were constructed using a rod and loop strategy, in which the H2L ligand served as the loop and the N-donor ligands (bpp, 1,4-bimb, 1,3-bimb, bpb, bpdp and bpeb; bpp = 1,3-di(pyridin-4-yl)propane; 1,4-bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene; 1,3-bimb = 1,3-bis((1H-imidazol-1-yl)methyl)benzene; bpb = 1,4-di(pyridin-4-yl)benzene; bpdp = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene; bpeb = 1,4-bis[2-(4-pyridyl)ethenyl]benzene) acted as the rods. All the complexes except 6 possessed binuclear secondary building units (SBUs) and displayed the same topologies. In compounds 1–4, two paddle-wheel Zn2 units were linked by two L ligands to form rhombic [Zn4L2] units and these units propagated into a chain-like motif. The N-donor ligands supported the chain-like structure and expanded into 2D layers. Three layers were interpenetrated forming a 2D + 2D → 2D polycatenation backbone. The 2D polycatenation layers were further packed into a 3D structure by hydrogen bonds and unconventional interactions. Compound 6 showed a 3D pillar-layer structure consisting of a four-fold interpenetrated network. This coordination polymer had an accessible volume of 38% for the fully desolvated structure and exhibited strong fluorescence that was selectively quenched by CrVI ions in aqueous solution at low concentrations.

As well known, poly (vinyl alcohol) (PVA) forms the various kinds of iodine complexes (forms I, II and III) when the sample is immersed in the KI/I2 aqueous solution of various iodine concentrations of 0.1–3 M. By immersing the PVA sample in more dilute solution of 0.001–0.05 M, a new X-ray diffraction pattern has been found (form IV). The quantitative analysis of the X-ray diffraction pattern combined with the resonance Raman data and the density functional theoretical calculation allowed us to derive the concrete structure model of form IV. The vertically-arrayed linear I5− ions are surrounded by the 6 PVA chains of planar-zigzag conformation to form the cylindrical structure. These cylinders are gathered together to form the hexagonal lattice. On the basis of the thus-determined structural information of a series of complexes, the transformation mechanism has been proposed for forms IV, I, II and III. Besides, the X-ray diffraction pattern of form IV was found to be similar to that measured for a commercial polarizer. The inner structure of the polarizer has been discussed concretely using the thus-revealed aggregation structure of form IV.

Mesangial proliferative glomerulonephritis (MsPGN) is characterized by mesangial cell proliferation, inflammation, and extracellular matrix deposition in the mesangial area, which develops into glomerulosclerosis and contributes to end-stage renal disease. Justicidin B is a bioactive compound isolated from Justicia procumbens L., a traditional herbal remedy that reduces proteinuria in nephritis. However, the mechanism of Justicidin B’s therapeutic effect on MsPGN remains unclear. This study was aimed to explore the positive effect of Justicidin B on MsPGN. The results showed that Justicidin B attenuated the proliferation induced by platelet-derived growth factor-BB (PDGF-BB) in MCs and blocked cell cycle progression. Likewise, inflammatory factors, including monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor alpha (TNF-α), in MCs were decreased after treatment with Justicidin B. In addition, Justicidin B exhibited antioxidant activity in PDGF-BB-induced MCs, shown by the decreased production of malondialdehyde and T-AOC, and increased the expression of superoxide dismutase. Besides, Justicidin B suppressed extracellular matrix (ECM) deposition by reducing the protein levels of collagen IV and fibronectin. Furthermore, we found that Justicidin B significantly inhibited activation of the Akt/mammalian target of rapamycin (mTOR) signaling pathway in MCs induced by PDGF-BB, but enhanced the levels of proteins in the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway. Taken together, Justicidin B prevented PDGF-BB-induced proliferation, inflammation, oxidative stress, and ECM accumulation via regulating the activation of the Nrf2/HO-1 pathway and the Akt/mTOR signaling pathway.

Five cobalt(II) complexes based on 1H-indazole-3-carboxylic acid (H2L), [Co(phen)(HL)2]·2H2O (1), [Co(5,5'-dimethyl-2,2'-bipy)(HL)2] (2), [Co(2,2'-bipy)2(HL)2]·5H2O (3), [Co2(2,9-dimethyl-1,10-phen)2(L)2] (4) and [Co2(6,6'-dimethyl-2,2'-bipy)2(L)2]·H2O (5) (2,2'-bipy =2,2'-bipyridine, phen =1,10-phenanthroline), have been synthesized and structurally characterized by elemental analyses, IR and UV-vis spectroscopies and single-crystal X-ray crystallography. The results indicate that 1-3 possess mononuclear Co(II) structures, while 4 and 5 exhibit binuclear structure. 1D water tape which is linked by the multiple hydrogen bonds was embedded in the 3D motif of complex 3. Complexes 4 and 5 show two orthogonal planes of motif that was constituted by phen/2,2'-bipy and indazole acid, respectively. The intermolecular interactions including hydrogen bonding and π-π stacking interactions are stabilizing these complexes. The interactions of the synthesized complexes with calf-thymus DNA (CT-DNA) have been investigated by UV-vis absorption titration, ethidium bromide displacement assay and viscosity measurements. The results reveal that the complexes could interact with CT-DNA via a groove binding mode. Their behavior rationalization was further theoretically studied by molecular docking.

Device scaling of partially depleted (PD) silicon-on-insulator (SOI) has the potential to increase speed. However, the increased gate tunneling and capacitance will complicate device behaviors and increase the difficulty in characterization for modeling purpose. For the first time, gate-bulk leakage current Igb and gate capacitance Cgg characterization methodology for PD SOI floating-body (FB) CMOS with high accuracy is proposed and verified in 40-nm SOI devices. These devices are with ultrathin equivalent oxide thickness of 12A, and radio frequency-capacitance voltage (RF-CV) technique is used for Cgg measurement to overcome the impact of leaky gate current. This methodology can eliminate properly the parasitic elements due to the coexistence of opposite poly gate type in the SOI T-shape body-tied device and accurately characterize and model Igb and Cgg behaviors for the PD SOI FB devices. Test patterns are designed with RF ground-signal-ground configuration and same test patterns can be used for both Igb and Cgg characterization. Impact of Igb and Cgg changes on the history effect, and speed and body potential is analyzed by BSIMSOI4.0 models. Simulation accuracy of history effect will have at least 3% improvement with this proposed methodology.

In this paper, a simple and nondestructive method of modeling 40-nm interconnects is proposed. Traditional methods based on charge-based capacitance measurement model the interconnects by fitting the capacitance or resistance curves, first by assuming one constant process parameter, such as metal thickness, and then by extracting the metal width, metal spacing, and interlevel dielectric (ILD) thickness from certain test patterns that may therefore result in model inaccuracy while the transmission and scanning electron microscopy methods are both destructive and time consuming. The proposed new methodology directly extracts the metal width based on the metal resistance test structures, and then the metal thickness, metal spacing, and ILD thickness without any presumption. It is also nondestructive and fast, with a model accuracy higher than 95%. Furthermore, with the ensured accuracy of layout parameter extraction, the necessity of an accurate interconnect model in the 40 nm technology and beyond is emphasized.

We successfully developed and verified a complete compact model solution for layout dependent effect (LDE) of FinFET technology. LDE has significant impact on the device performances mainly due to the application of stressors and aggressive device scaling. With LDE, performance degradation may be up to 10% or more. In this work, compact model solution for Length of Oxidation (LOD), Well Proximity Effect (WPE), Neighboring Diffusion Effect (NDE), Metal Boundary Effect (MBE), and Gate Line End Effect (GLE) were delivered. This solution was implemented successfully in BSIM-CMG for efficient circuit simulation.

A novel Schottky barrier silicon-on-insulator metal–oxide–semiconductor field-effect transistor featuring metallic source/drain and an electrical drain junction has been fabricated and characterized. The formation of electrical drain junction, or the field-induced drain (FID), is controlled by a metal field-plate overlying the passivation oxide. Excellent ambipolar operation is demonstrated on the device. Specifically, on/off current ratios up to 10 8 and 10 7 are observed for p- and n-channel operations, respectively. Meanwhile, the off-state leakage current shows very weak dependence on the voltage difference between the main-gate and the drain, highlighting the effectiveness of FID. Finally, negative differential conductance effect is observed for n-channel operation, which is identified as due to dynamic hot electron trapping during device characterization. 2002 Elsevier Science Ltd. All rights reserved.

The feasibility of simultaneously etching n+, p+, and undoped polysilicon (poly-Si) materials by a commercial transformer coupled plasma (TCP) reactor has been investigated in this study. Response surface methodology (RSM) was used to optimize process parameters including pressure, TCP source power, bias power, and Cl2/HBr flow on the main etch step. Quantitative relationships between etching performance and process parameters were established. Our results indicate that there exists a process parameter window that meets the requirements of etching polysilicon with different doping types simultaneously. High etch rate, superior uniformity, good end point detection (EPD) characteristics and profile control can be simultaneously obtained with the optimized recipe, irrespective of the doping types. Furthermore, only minor plasma-induced damage is detected as monitored from antenna transistors' charge-to-breakdown (Qbd), threshold voltage and charge pumping current.

The effects of rapid thermal annealing (RTA) performed after source/drain (S/D) implantation on the characteristics of complementary metal-oxide-semiconductor (CMOS) transistors with a TiN metal gate were investigated thoroughly. It was shown that n-channel devices require a higher thermal budget in order to reduce junction leakage, compared to p-channel devices. It was also found that the flat-band voltage and oxide thickness are both affected by the annealing temperature, particularly for p-channel devices. In n-channel devices, the gate leakage current level is highly dependent on channel length and RTA temperatures. Further analysis indicated that the agglomeration phenomenon during the high-temperature RTA step occurs more easily as the metal gate length becomes narrower. When this happens, gate oxide integrity is degraded, resulting in an increased gate leakage of n-channel transistors.

Charging damage induced in oxides with thickness ranging from 8.7 to 2.5 nm is investigated. Results of charge-to-breakdown ( Q bd ) measurements performed on control devices indicate that the polarity dependence increases with decreasing oxide thickness at both room and elevated temperature (180°C) conditions. As the oxide thickness is thinned down below 3 nm, the Q bd becomes very sensitive to the stressing current density and temperature. Experimental results show that severe antenna effect would occur during plasma ashing treatment in devices with gate oxides as thin as 2.6 nm. It is concluded that high stressing current level, negative plasma charging, and high process temperature are key factors responsible for the damage.

A simplified and improved Schottky-barrier metal-oxide-semiconductor device featuring a self-aligned offset channel length, PtSi Schottky junction, and reduced oxide thickness underneath the sub-gate was proposed and demonstrated. To alleviate the drawbacks related to the nonself-aligned offset channel length in the original version, a self-aligned offset channel length is achieved in the new device by forming the silicide source/drain junction self-aligning to the sidewall spacers abutting the gate. This results in not only one mask count saving but also better device performance, as facilitated by the reduced offset channel length of the self-aligned sidewall spacers. Moreover, the adoption of PtSi for the Schottky junction further improves the on-state current of p-channel operation, while a thinner oxide employed underneath the sub-gate effectively reduces the sub-gate bias needed to form the electrical junction to below 5 V. Significant improvement in on-current as well as leakage current reduction is achieved in the new improved device.

A novel Schottky barrier silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistor (MOSFET) device was proposed and demonstrated. The new device features a silicide source/drain and field-induced source/drain (S/D) extensions. Excellent ambipolar performance with a near-ideal sub-threshold slope (~ 60 mV/decade) and high on-/off-state current ratio (comparable to or higher than 109) is realized, for the first time, on a single device. These encouraging results suggest that the new device may be suitable for some niche applications requiring simple and low-temperature processing of complementary metal-oxide-semiconductor (CMOS)-like devices.

For the first time, an efficient methodology to accurately characterize the gate-bulk leakage current (I gb ) and gate capacitance (C gg ) of PD SOI floating body (FB) devices was proposed and demonstrated in 40-nm PD SOI devices with ultra-thin oxide EOT 12A. By applying the RF testing skill for the proposed SOI test patterns, we can eliminate properly the parasitic elements due to the co-existence opposite poly gate type the SOI T-shape body-tied (BT) device and accurately characterize and model the SOI FB I gb and C gg behaviors. Impact on the history effect was analyzed by BSIMSOI4.0 model. History effect analysis with high pulse and low pulse width was shown. Improvement of more than 3% simulation accuracy for history effect was also demonstrated.

Monitoring of plasma charging damage in ultrathin oxides (e.g.

The characteristics of a novel nano-scale silicon-on-insulator (SOI) device featuring silicide Schottky source/drain and field-induced S/D extensions induced by a sub-gate were investigated. The new device exhibits unique and high-performance bi-channel operation capability. In this work, particular attention was paid to the effects of subgate bias on the device operation. It is shown that the applied sub-gate voltage not only increases the on-state current, but also effectively suppresses the off-state leakage. Extremely high on/off current ratio (>10/sup 9/) has thus been obtained. Dependences of sub-gate bias on sub-threshold swing and threshold-voltage roll-off characteristics were also explored.

A novel nano-scale SOI device featuring silicide Schottky source/drain and field-induced S/D extensions is proposed and demonstrated. Excellent p- and n-channel performance with nearly ideal subthreshold swing (/spl sim/ 60 mV/dec.) and high on-/off-state current ratio (>10/sup 9/ and >10/sup 8/ for n- and p-channel modes, respectively) is realized, for the first time, on a single device. These encouraging results suggest that the new device may represent a potential alternative to post-CMOS device applications.

The effects of rapid-thermal annealing (RTA) after source/drain (S/D) implant on the characteristics of CMOS transistors with sputtered TiN gate were investigated. Our results indicate that n/sup +//p junctions need higher thermal budget than p/sup +//n junctions to achieve low leakage performance. It was also found from C-V measurements that the flat-band voltage and oxide thickness are both affected by the annealing treatment, especially for p-channel devices. A hump in the subthreshold characteristics of p-channel transistors is observed, due to the existence of a leakage path along the isolation edge. It is also shown that the agglomeration phenomenon is easier to incur during the high-temperature RTA step as the metal gate width becomes narrower. When this happens, gate oxide integrity is degraded, resulting in increased gate leakage of n-channel transistors.

Recently, we proposed and demonstrated a novel Schottky barrier (SB) poly-Si thin-film transistor (TFT) that exhibits excellent ambipolar operation performance. In this work, we extend the idea to the fabrication of SB SOI devices. The new device employs a field-plate (or sub-gate) to induce an electrical drain extension in the active layer. The unique field-induced drain (FID) feature reduces effectively the off-state leakage current, while maintaining a reasonable on-current, resulting in significant improvement in the device performance.

A novel thin-film transistor (TFT) device that requires no implant step and is capable of ambipolar operation is proposed and successfully demonstrated. The new structure features an undoped Si active channel, a tap metal field-plate (i.e., the sub-gate), and Schottky source/drain. The equivalent circuit of the device is given. During device operation, a high fixed voltage is applied to the sub-gate to form a field-induced source/drain layer under the sub-gate region. Depending on the polarity of the sub-gate bias, the device can be set for n-channel operation with positive sub-gate bias, and p-channel operation with negative sub-gate bias. The new device is similar to conventional Schottky barrier (SB) MOSFET devices, with the exception of a field-induced source/drain region between the channel and Schottky source/drain. The existence of the field-induced source/drain region serves to supply abundant channel carriers during on-state, while reducing the notorious off-state leakage that has plagued all previous SB MOSFETs. The new device is also similar to MOSFETs with field-induced drain (FID), except that the heavily-doped source/drain region is replaced by Schottky source/drain. While retaining all the advantages of FID such as low off-state leakage and low junction leakage, the use of Schottky source/drain not only reduces processing steps (i.e., implant and annealing), but also allows ambipolar operation, thus greatly simplify processing steps especially for CMOS process integration.

Poly-Si Schottky-barrier thin-film transistors (SB-TFTs) were fabricated and characterized. In this study, SB-TFTs were first fabricated by using a conventional sidewall spacer to isolate the gate and S/D regions during salicidation. However, it was found that these SB-TFTs depict very poor on/off current ratio (3) as well as severe GIDL (gate-induced drain leakage)-like leakage current. To overcome these shortcomings, a novel SB-TFT structure is also fabricated in this study to improve the device performance. The new device consists of a field-induced-drain region (FID), which is an offset drain region controlled by a metal field-plate lying on top of the passivation oxide. The FID region is sandwiched between the silicided drain and the active channel region. Carrier types and the conductivity of the transistor are controlled by the metal field-plate. Since the metal field plate is formed simultaneously with the regular metal patterning, no additional processing steps are required. Our results show that the new device can significantly improve the on/off current ratio to over 106 for both p- and n-channel operations, while effectively eliminating the GIDL-like leakage.

In this paper, we report the use of shallow germanium halo doping on improving the short-channel effects of deep submicron n-channel metal-oxide-semiconductor field effect transistors. It is demonstrated that by adding a shallow (i.e., 10 keV) germanium large-angle-tilt implant (LATID), V th lowering in short-channel transistors is significantly improved. The improvement is found to increase with increasing germanium dose. A low germanium dose (e.g., 5×1012 cm-2) is also found to effectively improve the drain-induced barrier lowering (DIBL) of the short-channel transistors. Our results also show that junction leakage degradation, which has been previously reported to accompany germanium implants using higher energy, can be minimized by the shallow low-dose implant used in this study.

The authors report the effects of N2O-annealed sacrificial oxide on nMOSFETs. It is demonstrated that by adding an N2O-annealing step to the sacrificial oxide which was stripped off before growing the final gate oxide, the reverse short-channel effects (RSCE) can still be effectively suppressed.