Higher Lowest Unoccupied Molecular Orbital Research Articles

Achieving 17.7% Efficiency of Ternary Organic Solar Cells by Incorporating a High Lowest Unoccupied Molecular Orbital Level and Miscible Third Component

A ternary strategy has been demonstrated as being an effective method to improve the power conversion efficiency (PCE); however, general rules for materials selection are not fully comprehended. Herein, nonfullerene acceptor ITIC‐M and fullerene acceptor PC70BM possessing higher lowest unoccupied molecular orbital (LUMO) and good miscibility with nonfullerene acceptor Y7 are incorporated as third components in the state‐of‐the‐art of PM6:Y7 binary blend. As a result, the device PCE for both ternary devices improves from 16.46% for binary host to 17.73% and 17.67% for ITIC‐M‐ and PC70BM‐based ternary devices, respectively. The higher LUMO of the guest acceptor can play multiple roles to elevate the open‐circuit voltage such as reducing energy‐loss and reverse saturation current, creating less‐localized shallow trap sites along with suppressing charge recombination, and decreasing Urbach energy. Moreover, the good miscibility facilitates an alloy‐like phase in acceptors domain for efficient exciton dissociation and electron transport, which leads to improved short‐circuit current density and fill factor in ternary devices. The results provide a promising approach to realize high‐performance ternary organic solar cells by synergizing the compatible third component with host acceptor.

Third component with a high LUMO energy level enables 17.69% efficiency in ternary organic solar cells

The ternary strategy is thought to be a practical method for improving the power conversion efficiency (PCE) of organic solar cells (OSCs). To create ternary OSCs, a PM6:BTP-BO-4F host blend was combined with the non-fullerene small molecule acceptor BTA3, which has a high lowest unoccupied molecular orbital (LUMO). BTA3 demonstrated complementary absorption spectra and excellent compatibility with BTP-BO-4F, which made it easier to modulate the ternary film's morphology and catch more photons. As a result, the short circuit current density increased. Additionally, BTA3's LUMO level was marginally higher than BTP- BO-4F's, which led to a higher open-circuit voltage of the TOSCs. The addition of BTA3 improved the OSCs' energy transfer and phase separation, which in turn sped up charge transfer and reduced exciton recombination. The PCE of the TOSCs included with 10 wt% BTA3 rose to 17.69% in comparison to a PCE of 16.46% based on host binary OSCs. This research demonstrated that the incorporation of BTA3 with a high LUMO level enabled the fabrication of ternary OSCs with good performance.

Molecular Optimization on Polymer Acceptor Enables Efficient All-Polymer Solar Cell with High Open-Circuit Voltage of 1.10V.

Currently, rational design of polymer acceptors is desirable but there is still a challenge to develop high-performance all-polymer solar cells (all-PSCs). In this work, brominated thienyl-fused malononitrile-based monomer is employed to copolymerize with indacenodithiophene (IDT) and benzodithiophene (BDT)-based linking units to develop two polymerized small molecule acceptors (PSMAs) PIDT and PBDT, respectively, for all-PSCs. The two PSMAs show similar absorption edges, while PBDT shows a slightly higher lowest unoccupied molecular orbital (LUMO) energy level than PIDT. Benefitted from the relatively high LUMO levels of the two polymer acceptors, notable open-circuit voltage (Voc ) values over 1.0V are achieved when using them as acceptor to blend with PTQ10 as polymer donor. Particularly, the all-PSC based on PTQ10:PIDT demonstrates a power conversion efficiency of 10.19%, with an outstanding Voc of 1.10V benefitted from the higher LUMO energy level of PIDT acceptor. The results demonstrate a feasible strategy to design PSMAs by selecting appropriate linking units for increasing the Voc and improving the efficiency of all-PSCs.

High-Performance Ternary Polymer Solar Cells Enabled by a New Narrow Bandgap Nonfullerene Small Molecule Acceptor with a Higher LUMO Level.

Obtaining a large open-circuit voltage (VOC ) and high short-circuit current density (JSC ) simultaneously is important in improving power conversion efficiency (PCE) of organic photovoltaics. The ternary strategy with using a higher lowest unoccupied molecular orbital (LUMO) level nonfullerene acceptor (NFA) guest can achieve increased VOC , yet JSC is decreased or maintained, so it's still a challenge to offer increased VOC and JSC values concurrently via the newly presented VOC -increased ternary strategy. To overcome this issue, a new narrow bandgap NFA TT-S-4F is reported by introducing 3,6-dimethoxylthieno[3,2-b]thiophene (TT) as π-spacers to connect electron-rich core with terminal groups, so as to upshift the LUMO level and extend π-system. When adding 10% TT-S-4F into binary system based on PTB7-Th:IEICO-4F, the higher-LUMO-level of TT-S-4F, the increased charge mobilities, the reduced trap-assisted combination loss, and a finer nanofiber structure and increased phase separation size are obtained, which simultaneously promotes JSC , VOC , and fill factor (FF), thus obtaining an optimal PCE (12.5%vs 11.5%). This work illustrates that an extending conjugated backbone with large π-spacers and inclusion of alkylthiophenyl side-chains is a concept to synthesize NFA guests for use on the VOC -increased ternary strategy that enables to realize simultaneously increased JSC , VOC , and FF.

Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells

It is widely known that the miscibility between donor and acceptor is a crucial factor that affects the morphology and thus device performance of nonfullerene organic solar cells (OSCs). In this Letter, we show that incorporating a third component with lower miscibility and higher lowest unoccupied molecular orbital (LUMO) level into the state-of-the-art PM6:Y6 system can significantly enhance the performance of devices. The best results of the ternary devices are achieved by adding a small molecular acceptor named ITCPTC (similar to 5% w/w), which significantly improves the power conversion efficiency (PCE) of the host system from 16.44% to 17.42%. The higher LUMO of the third component increases the open-circuit voltage (V-oc), while the low miscibility enlarges the domains and leads to improved short-circuit current density (J(sc)) and fill factor (FF). The efficacy of this strategy is supported by using other nonfullerene third components including an asymmetric small molecule (N7IT) and a polymer acceptor (PF2-DTC), which play the same role as ITCPTC and boost the PCEs to 16.96% and 17.04%, respectively. Our approach can be potentially applied to a wide range of OSC material systems and should facilitate the development of the OSC field.

PffBT4T-2OD Based Solar Cells with Aryl-Substituted N-Methyl-Fulleropyrrolidine Acceptors.

Novel C60 and C70 N-methyl-fulleropyrrolidine derivatives, containing both electron withdrawing and electron donating substituent groups, were synthesized by the well-known Prato reaction. The corresponding highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels were determined by cyclic voltammetry, from the onset oxidation and reduction potentials, respectively. Some of the novel fullerenes have higher LUMO levels than the standards PC61BM and PC71BM. When tested in PffBT4T-2OD based polymer solar cells, with the standard architecture ITO/PEDOT:PSS/Active-Layer/Ca/Al, these fullerenes do not bring about any efficiency improvements compared to the standard PC71BM system, however they show how the electronic nature of the different substituents strongly affects the efficiency of the corresponding organic photovoltaic (OPV) devices. The functionalization of C70 yields a mixture of regioisomers and density functional theory (DFT) calculations show that these have systematically different electronic properties. This electronic inhomogeneity is likely responsible for the lower performance observed in devices containing C70 derivatives. These results help to understand how new fullerene acceptors can affect the performance of OPV devices.

Determinant factors of photocatalytic hydrogen evolution activity for Schiff-base conjugated polymers

Conjugated polymers are promising catalysts for photocatalytic hydrogen evolution (PHE) from water. Here, a series of imine-linked conjugated polymers were synthesized via Schiff-base condensation using an easy and low-temperature protocol with cheap raw materials and green solvent. Several readily available diaminobenzene with different amino substitution positions on the phenyl ring were used to react with terephthalaldehyde, leading to formation of polymers varying from one dimensional (1D) nanorods to two dimensional (2D) and three-dimensional (3D) networks. The obtained polymer with 1D crystalline structure was found to show the highest hydrogen production rate at ~24.3 μmol/h under visible light irradiation (λ > 420 nm) without adding any additional metal co-catalysts. Detailed analysis of the structure, morphology and photoelectron-chemical properties of these as-synthesized polymers leads to the conclusion that 1D nanorods and high LUMO (the lowest unoccupied molecular orbital) play more important roles than large conjugation and surface area in improving the PHE capacity of polymer. This study illustrated a protocol for the production of metal-free photocatalyst synthesized using cheap and green solvent at low-temperature.

Nonfullerene Acceptor with "Donor-Acceptor Combined π-Bridge" for Organic Photovoltaics with Large Open-Circuit Voltage.

In this work, a kind of "donor-acceptor (D-A) combined π-bridge" based on the regioselective reactivity of monofluoro-substituted benzothiadiazole (FBT) to link a thiophene ring has been designed to construct a new A-π-D-π-A-type small molecular acceptor (IDT-FBTR) with indacenodithiophene (IDT) as a central core (D) and 3-octyl-2-(1,1-dicyanomethylene)rhodanine as an electron-withdrawing terminal group (A). Because of the strong intramolecular push-pull electron effect, the IDT-FBTR shows a strong and broad intramolecular charge-transfer absorption band in the range of 500-750 nm. Especially, as an electron-deficient FBT unit (A') and an electron-rich thiophene ring (D') in "D-A combined π-bridge" exert an "offset effect" to regulate the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy levels of the molecule, a relatively high LUMO energy level can be maintained for IDT-FBTR that is helpful to enhance the open-circuit voltage ( Voc) for highly efficient organic solar cells (OSCs). Therefore, the optimized OSC device based on IDT-FBTR as the acceptor and PTB7-Th as the donor shows a much high Voc of 1.02 V with a relatively low Eloss of 0.56 eV and a best power conversion efficiency of 9.14%.

Polymer Electron Acceptors Based on Iso‐Naphthalene Diimide Unit with High LUMO Levels

The lowest unoccupied molecular orbital (LUMO) energy level (ELUMO) is a key parameter for polymer electron acceptors of all‐polymer solar cells (all‐PSCs). The state‐of‐the‐art polymer electron acceptors based on 1,4,5,8‐naphthalenediimide (NDI) unit suffer from low‐lying ELUMO, which leads to low open‐circuit voltage (VOC) of all‐PSCs. In this manuscript, the authors use 1,2,5,6‐naphthalenediimide (iso‐NDI) unit to develop a series of polymer electron acceptors with high‐lying ELUMO. Their thermal, optical, electrochemical, and charge transporting properties are systematically investigated and their applications in all‐PSCs are explored. The polymer based on iso‐NDI unit and bithiophene unit exhibits the ELUMO of −3.50 eV, which is higher than that of the corresponding polymer based on NDI unit (ELUMO = −3.86 eV) by 0.36 eV. As a result, the all‐PSC devices exhibit VOC enhancement by 0.30 V. All‐PSC devices of these polymer electron acceptors with poly(3‐hexylthiophene) as the electron donor show the VOC of 0.90 V and power conversion efficiency of 0.27%. These results indicate that iso‐NDI unit is a promising building block to design polymer electron acceptors for all‐PSCs with high VOC. image

Evaluating the influence of heteroatoms on the electronic properties of aryl[3,4-c]pyrroledione based copolymers

A donor-acceptor-type conjugated copolymer (PBDT-PPD) composed of benzodithiophene (BDT) and pyrrolopyrroledione (PPD) was synthesized using the Stille cross-coupling reaction. Using both experimental and theoretical data, the optical, electrochemical, and photovoltaic properties of PBDT-PPD were compared with those of its sulfur analog, PBDT-TPD, which is composed of BDT and thienopyrroledione (TPD). The optical bandgaps of the polymers were determined to be 1.86 and 2.20 eV, respectively. While both materials possessed similar highest occupied molecular orbital (HOMO) levels, the lowest unoccupied molecular orbital (LUMO) level for PBDT-PPD was raised relative to that of PBDT-TPD. Devices incorporating PBDT-PPD had a higher open-circuit voltage and fill factor, yet drastically lower short-circuit current density (Jsc) than PBDT-TPD leading to a lower power conversion efficiency (PCE). The lack of significant intramolecular charge transfer (ICT) combined with the high LUMO of PBDT-PPD resulted in poor spectral overlap with the solar spectrum, lowering Jsc. Additionally, there was poor electron injection into PCBM, which also reduced the PCE.

Electronic transport properties of oligo phenylene ethynylene molecule modified by the (CH3)2 and (NH2)2 groups

The modification effects of the groups (CH3)2 and (NH2)2 on the oligo phenylene ethynylene (OPE) molecules with single and double S atoms connected to the two electrodes are investigated by the density functional theory and non-equilibrium Green function. The modified OPE molecule is optimized and used to build a two-probe system with Au electrodes. Then the two-probe system is fully relaxed to obtain a stable structure. The electronic transport properties of the two-probe system are also calculated with the non-equilibrium Green function method. The calculation results show that both the modified groups and the bridge atoms can lead to the switch effect, the negative differential resistance behavior, and the rectifying behavior for the two-probe system. When molecules are connected with single S atom at one end, both the (NH2)2-OPE and the (CH3)2-OPE molecules show the rectifying behavior. However, the (NH2)2-OPE also shows a switch effect at larger voltage because there is current when the negative bias is over 1.3 V, while the (CH3)2-OPE molecule demonstrates a complete rectifying behavior because it is hardly conductive in the whole positive bias area. The current of OPE molecule without modification group always increases with the increase of voltage. Therefore, it is only a resistance. These results are different from that of NO2-OPE-NH2 molecule which shows a negative differential resistance behavior. For the case of the molecule connected with S atoms at both ends, the (NH2)2-OPE(S) and (CH3)2-OPE(S) models show negative differential resistance behaviors in the negative bias range. It is found that both (NH2)2-OPE and (CH3)2-OPE molecules demonstrate the negative differential resistance behaviors when they are connected with S atoms bridge at both ends. However, the current of the molecule with one S atom at one end is about two-order magnitude lower than that of the molecule with S atoms at both ends. It is shown that S atom acting as a bridge can significantly affect the characteristic of current-voltage. The mechanisms for the various characteristics of the electronic transport properties are explored by analyzing the projection orbit electron distribution, the transmission spectrum, and the density of states under the different bias voltages. For (NH2)2-OPE molecule with a single S atom at one end in the negative bias range, only the lowest unoccupied molecular orbital (LUMO) can transfer electron with low bias, but both highest occupied molecular orbital (HOMO) and LUMO can be conductive with high bias, which results in the switch effect. In the positive bias range, both HOMO and LUMO cannot be conductive with low bias, while LUMO can be conductive with high bias, which results in the switch behavior. For the case of (NH2)2-OPE molecule with one S atom at each end, only the HOMO can transfer electron in the low bias range, while the LUMO can be conductive at high positive bias, but both HOMO and LUMO cannot be conductive in high negative bias range, which leads to the non-symmetric negative differential resistance effect in the whole bias range. A similar analysis of the difference between HOMO and LUMO can be used to understand the characteristics of the current-voltage of (CH3)2-OPE. Considering the fact that the different modification groups can lead to various current-voltage properties of OPE molecule, the modified OPE molecule is a promising candidate for designing molecule device.

Study of N–Ag–Zn/TiO2, N–Ag–Zr/TiO2 with N719 and P3OT co-sensitization effect on the performance of dye-sensitized solar cell

Nanocrystal N–Zn/TiO2 and N–Zr/TiO2 anode films were prepared using TiCl4 as raw material and doping Zn and Zr on the N/TiO2. Furthermore, Ag was loaded on the nanocrystal N–Zn/TiO2 and N–Zr/TiO2 anode films by photodeposition technology in which AgNO3 solution was irradiated by UV light. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and X-ray photoelectron spectroscopy measurements were performed, which show Zn are doped into TiO2 and Ag are loaded on N–Zn/TiO2 anode film successfully. The cyclic voltammetry results show that the composite dye P3OT/N719 has a higher LUMO (lowest unoccupied molecular orbital) and has a better performance of the DSSCs (dye-sensitized solar cells) based on N–Ag–Zr/TiO2 anode film. In addition, when the DSSCs assembled with anode film, the photoelectric conversion efficiency was increased to 4.11 %.

Highly Efficient and Low Turn-On Voltage Quantum Dot Light-Emitting Diodes by Using a Stepwise Hole-Transport Layer.

Highly efficient red quantum dot light-emitting diodes (QD-LEDs) with a very high current efficiency of 16 cd/A were demonstrated by adopting stepwise hole-transport layers (HTLs) consisting of 4,4'-N,N'-dicarbazole-biphenyl (CBP) combined with N,N'-dicarbazolyl-3,5-benzene (mCP). The mCP layer plays two important roles in this kind of QD-LEDs. One is that it can block the electron to leak into the HTL due to its higher LUMO (LUMO = the lowest unoccupied molecular orbital) energy level than that of CBP; and the other is it can separate the carrier accumulation zone from the exciton formation interface, which is attributed to the stepwise hole-transport layer structure. Moreover, the lower HOMO (HOMO = the highest occupied molecular orbital) energy level of mCP decreases the hole-injection barrier from the HTL to the QD emitting layer, which improves the charge carrier balance injected into the QD layer, reducing the turn-on voltage of QD-LEDs fabricated with the stepwise HTL structure.

Effect of Fullerene Tris-adducts on the Photovoltaic Performance of P3HT:Fullerene Ternary Blends

Fullerene tris-adducts have the potential of achieving high open-circuit voltages (V(OC)) in bulk heterojunction (BHJ) polymer solar cells (PSCs), because their lowest unoccupied molecular orbital (LUMO) level is higher than those of fullerene mono- and bis-adducts. However, no successful examples of the use of fullerene tris-adducts as electron acceptors have been reported. Herein, we developed a ternary-blend approach for the use of fullerene tris-adducts to fully exploit the merit of their high LUMO level. The compound o-xylenyl C60 tris-adduct (OXCTA) was used as a ternary acceptor in the model system of poly(3-hexylthiophene) (P3HT) as the electron donor and the two soluble fullerene acceptors of OXCTA and fullerene monoadduct (o-xylenyl C60 monoadduct (OXCMA), phenyl C61-butyric acid methyl ester (PCBM), or indene-C60 monoadduct (ICMA)). To explore the effect of OXCTA in ternary-blend PSC devices, the photovoltaic behavior of the device was investigated in terms of the weight fraction of OXCTA (W(OXCTA)). When W(OXCTA) is small (<0.3), OXCTA can generate a synergistic bridging effect between P3HT and the fullerene monoadduct, leading to simultaneous enhancement in both V(OC) and short-circuit current (J(SC)). For example, the ternary PSC devices of P3HT:(OXCMA:OXCTA) with W(OXCTA) of 0.1 and 0.3 exhibited power-conversion efficiencies (PCEs) of 3.91% and 3.96%, respectively, which were significantly higher than the 3.61% provided by the P3HT:OXCMA device. Interestingly, for W(OXCTA) > 0.7, both V(OC) and PCE of the ternary-blend PSCs exhibited nonlinear compositional dependence on W(OXCTA). We noted that the nonlinear compositional trend of P3HT:(OXCMA:OXCTA) was significantly different from that of P3HT:(OXCMA:o-xylenyl C60 bis-adduct (OXCBA)) ternary-blend PSC devices. The fundamental reasons for the differences between the photovoltaic trends of the two different ternary-blend systems were investigated systemically by comparing their optical, electrical, and morphological properties.

Solution-Processable Triindoles as Hole Selective Materials in Organic Solar Cells

We report the use of two solution-processable triindoles, triazatruxene (TAT), and N-trimethyltriindole (TMTI), as hole selective materials in organic solar cells. The unique optical and electronic properties of these molecules make them suitable as a hole extracting/electron blocking layer, i.e. transparency in the visible region due to a wide bandgap, high LUMO (lowest unoccupied molecular orbital) energy level, modest HOMO (highest occupied molecular orbital) level, and high hole carrier mobility. TAT is shown to have a LUMO at -1.68 eV, a HOMO at -5.03 eV, and a bandgap of 3.35 eV, whereas TMTI has a LUMO at -2.05 eV, a HOMO at -5.1 eV, and a bandgap of 3.05 eV, obtained from cyclic voltammetry measurements and absorption spectroscopy. Planar heterojunction photovoltaic devices, consisting of a solution processed transparent TAT (or TMTI) layer and a vapor-deposited C60 layer, exhibited efficiencies of up to 0.71 % (or 0.87 %). In these bilayer devices, the excitons are primarily generated in the C60 layer and undergo dissociation in the interfaces via hole transfer from the C60 layer to the TAT (or TMTI) layer. Additionally, spin-casting methanol solution of TAT on the top of P3HT:PCBM bulk heterojunction in an inverted device produced a hole selective interfacial layer between the photoactive layer and anode, leading to a 26% efficiency increase as compared to a control device without the TAT layer.

Potential of bifluorenylidene derivatives as nonfullerene small-molecule acceptor for heterojunction organic photovoltaics: a density functional theory study

To maximize the efficiency of heterojunction organic photovoltaics (HJOPVs), it is imperative to increase not only the open-circuit voltage (VOC) but also the short-circuit current (ISC). Therefore, it is desirable to find an organic acceptor material that possesses a higher lowest unoccupied molecular orbital (LUMO) level for higher VOC and can absorb photons in the solar spectrum efficiently for larger ISC. In this paper, in comparison with the typical donor poly(3-hexylthiophene) (P3HT) and acceptor [6,6]-phenyl-C61-butyric acid ester ([60]PCBM), the geometries, electronic structures, absorption spectra, and transport properties of a series of organic compounds containing 9,9′-bifluorenylidene (9,9′BF) were systematically investigated using density functional and the semiclassical Marcus charge transfer theory calculation to evaluate their potential severing as acceptor. Our results indicate that the absorption spectra of 99′BF derivatives have better overlap with the solar spectrum than those of [60]PCBM, and higher LUMOs result in a significant enhancement of VOC when they are used in HJOPVs with P3HT as donor materials. On the other hand, these compounds own higher electron carrier mobilities comparing with [60]PCBM. The study also demonstrates that the H-shaped compounds based on the 99′BF backbone possess good photophysical and charge transport properties, can be promising organic semiconductor for heterojunction photovoltaics.

Highly Efficient and Thermally Stable Polymer Solar Cells with Dihydronaphthyl‐Based [70]Fullerene Bisadduct Derivative as the Acceptor

AbstractThe efficiency of polymer solar cells (PSCs) can be essentially enhanced by improving the performance of electron‐acceptor materials, including by increasing the lowest unoccupied molecular orbital (LUMO) level, improving the optical absorption, and tuning the material solubility. Here, a new soluble C70 derivative, dihydronaphthyl‐based C70 bisadduct (NC70BA), is synthesized and explored as acceptor in PSCs. The NC70BA has high LUMO energy level that is 0.2 eV higher than [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), and displays broad light absorption in the visible region. Consequently, the PSC based on the blend of poly(3‐hexylthiophene) (P3HT) and NC70BA shows a high open‐circuit voltage (Voc = 0.83 V) and a high power conversion efficiency (PCE = 5.95%), which are much better than those of the P3HT:PCBM‐based device (Voc = 0.60 V; PCE = 3.74%). Moreover, the amorphous nature of NC70BA effectively suppresses the thermally driven crystallization, leading to high thermal stability of the P3HT:NC70BA‐based solar cell devices. It is observed that the P3HT:NC70BA‐based device retains 80% of its original PCE value against thermal heating at 150 °C over 20 h. The results unambiguously indicate that the NC70BA is a promising acceptor material for practical PSCs.

Facile Synthesis of o-Xylenyl Fullerene Multiadducts for High Open Circuit Voltage and Efficient Polymer Solar Cells

The ability to control the lowest unoccupied molecular orbital (LUMO) level of an electron-accepting material is a critical parameter for producing highly efficient polymer solar cells (PSCs). Soluble bis-adducts of C60 have great potential for improving the VOC in PSCs because of their high LUMO level. In this work, we have developed a novel o-xylenyl C60 bis-adduct (OXCBA) via a [4 + 2] cycloaddition between C60 and an irreversible diene intermediate from α,α′-dibromo-o-xylene. OXCBA was successfully applied as the electron acceptor with poly(3-hexylthiophene) (P3HT) in a PSC, showing a high efficiency of 5.31% with VOC of 0.83 V. This composite showed a nearly 50% enhancement in efficiency compared to the P3HT:PCBM control device (3.68% with VOC of 0.59 V). Furthermore, tuning the molar ratio between C60 and the α,α′-dibromo-o-xylene group from 1:1 to 1:3 in the reaction scheme enables facile control over the number of o-xylenyl solubilizing groups ultimately tethered to the fullerene, thus producing o...

Relationships between Cellular Toxicity, the Maximum Tolerated Dose, Lipophilicity and Electrophilicity

Results on cellular toxicity and maximum tolerated dose (MTD) for rats and mice were available for approximately 175 chemicals tested by the US National Toxicology Program. Additionally, the computed log P (log octanol-water partition coefficient) and the lowest unoccupied molecular orbital (LUMO) energy values, a measure of electrophilicity were also available for most of these chemicals. Analysis of the chemicals on the basis of their physical and quantum chemical properties and their toxic effects on cultured cells and rodents showed that: 1) as a group, the more toxic chemicals showed a trend towards higher LUMO energies (i.e. less electrophilic); 2) cytotoxic chemicals exhibited increased lipophilicity; and 3) cytotoxic chemicals were associated with increased systemic toxicity (as measured by the MTD). None of these relationships was expressed in a significant linear fashion as a function of the concentration at which the chemicals exhibited cytotoxicity.