Rik Tykwinski

• University of Alberta

Two dimeric tetracene complexes, Pt(Ltc)2Cl2 and Pd(Ltc)2Cl2, have been synthesized by coordination of a pyridyl substituted acene‐ to a Pt(II) and Pd(II) metal center. The photophysical properties of the two dimers are characterized and compared with the free tetracene ligand Ltc, as well as the corresponding monomeric complexes (Pt(Ltc)(Lref)Cl2...

The synthesis of [3]‐ and [5]cumulenes bearing 4‐hexylphenyl endgroups, [3]PhHex and [5]PhHex , has been developed. The incorporation of alkyl groups is designed to enhance film formation by improving solubility. Although tetraaryl[3]cumulenes are typically quite stable, the head‐to‐tail dimerization of [3]PhHex is observed after prolonged storage...

Stimulus-responsive triplet excited states and multiexcitonic logic gates have garnered increasing interest. Singlet fission is an efficient multiple exciton generation process, in which one singlet converts into two triplets. Singlet fission is, however, rarely reported to be switchable by external stimuli. Here we design a meta-diethynylphenylene...

Conjugated alkynes are valuable intermediates in the synthesis of natural products, agrochemicals, pharmaceuticals, fine chemicals, and organic molecular materials. Since its introduction in 1975, the palladium‐catalyzed Sonogashira reaction has become the primary choice for the construction of sp–sp ² carbon–carbon bonds in aryl‐, heteroaryl‐, and...

Carbyne, the ideal linear atomic wire consisting of a single-atom thick chain of sp-carbon, is theoretically predicted to have around five times higher surface area than graphene, notable charge mobilities, as well as excellent optical and thermal properties. Despite these impressive properties, the exploitation of carbyne-like system as an electro...

6,13‐Diethynylpentacene derivatives with sterically bulky substituents (Tr*, tris(3,5‐di‐tert‐butylphenyl)methyl groups) appended to the ethynyl moieties at the 6‐ and 13‐positions have been synthesized, as well as derivatives with electron‐withdrawing fluorine groups on the 1,2,3,4,8,9,10,11‐positions. These molecules are designed to investigate r...

A Sn-mediated mechanochemical reductive aromatization of 1,4-dihydroxy- and 1,4-dimethoxy-cyclohexadienes has been used to form ten acenes, including derivatives of benzene, anthracene, tetracene, and pentacene. This method has been developed to overcome issues faced during the formation of electron-deficient 1,4-dihydroxy- or 1,4-dimethoxy-cyclohe...

We show an unexpected aggregation phenomenon of a long oligoyne (Py[16]) with 16 contiguous triple bonds and endcapped with bulky 3,5‐bi(3,5‐bis‐tert‐butylphenyl)pyridine groups. Aggregation of 1D π‐conjugated oligoyne chains is rare given the minimal π–π intermolecular interactions as well as its flexibility that works against self‐assembly. In di...

6,13-Diethynylpentacene derivatives with sterically bulky substituents (Tr*, tris(3,5-di-tert-butylphenyl)methyl groups) appended to the ethynyl moieties at the 6- and 13-positions have been synthesized, as well as derivatives with electron withdrawing fluorine groups on the eight pro-cata positions. These molecules are designed to investigate rela...

Chemical reduction of a [4]cumulene with cesium metal was explored, and the structural changes stemming from electron acquisition are detailed using X‐ray crystallography. It is found that the [4]cumulene undergoes dramatic geometric changes upon stepwise reduction, including bending of the cumulenic core and twisting of the endgroups from orthogon...

The synthesis and characterization of platinum(II) and palladium(II) complexes bearing two (dimers Pt(Lpc)2Cl2 and Pd(Lpc)2Cl2), one (monomers Pt(Lpc)(Lref)Cl2 and Pd(Lpc)(Lref)Cl2), or no (reference compounds Pt(Lref)2Cl2 and Pd(Lref)2Cl2) pentacene-based pyridyl ligands are presented. Photophysical properties of the dimers are probed by means of...

We present an experimental study investigating the solvent-dependent dynamics of a 9,10-bis(phenylethynyl)anthracene monomer, dimer, and trimer. Using transient absorption spectroscopy, we have discovered that triplet excited state formation in the dimer and trimer molecules in polar solvents is a consequence of charge recombination subsequent to s...

Photon energy conversion can be accomplished in many different ways, including the two opposing manners, down-conversion (i.e., singlet fission, SF) and up-conversion (i.e., triplet-triplet annihilation up-conversion, TTA-UC). Both processes have the potential to help overcome the detailed balance limit of single-junction solar cells. Tetracene, in...

In the present work, the energy donor 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) is used for the first time in combination with a pentacene dimer (Pnc2) to provide the conjugate BODIPYPnc2 that features absorption throughout a large part of the solar spectrum. Upon photoexcitation, the singlet excited state energy of BODIPY is transferred...

Photon energy conversion can be accomplished in many different ways, including the two opposing manners, down-conversion (i.e., singlet fission, SF) and up-conversion (i.e., triplet-triplet annihilation up-conversion, TTA-UC). Both processes have the potential to help overcome the detailed balance limit of single-junction solar cells. Tetracene, in...

The goal of harnessing the theoretical potential of singlet fission (SF), a process in which one singlet excited state is split into two triplet excited states, has become a central challenge in solar energy research. Covalently linked dimers provide crucial models for understanding the role of chromophore arrangement and coupling in SF. Sensitizer...

The synthesis of a ruthenium(II) tetramer (Ru(L[Formula: see text])[Formula: see text]Cl[Formula: see text] bearing pyridyl pentacene-based ligands and its corresponding model complex lacking pentacene moieties (Ru(L[Formula: see text])[Formula: see text]Cl[Formula: see text] is presented. The formation of these tetramers is corroborated by ¹ H, [F...

ConspectusThe formation and study of molecules that model the sp-hybridized carbon allotrope, carbyne, is a challenging field of synthetic physical organic chemistry. The target molecules, oligo- and polyynes, are often the preferred candidates as models for carbyne because they can be formed with monodisperse lengths as well as defined structures....

We report a general method for the desymmetrization of 6,13-pentacenequinone to access ethynylated pentacene ketones, namely, 13-hydroxy-13-(ethynylated)pentacene-6(13H)-ones. These pentacene ketones ("pentacenones") serve as divergent intermediates to unsymmetrically 6,13-disubstituted pentacenes, commonly used for studying singlet fission process...

The design and synthesis of persistent tetraaryl[4]cumulenes is reported. Derivatives with phenyl endgroups ([4]Ph and [4]Ph/Ar*) are susceptible to reactions during synthesis and/or purification that complicate isolation of the desired product, particularly intermolecular dimerization reactions. Incorporation of (3,5‐di‐tert‐butyl)phenyl endgroups...

We placed two pentacene chromophores at the termini of a diacetylene linker to investigate the impact of excitation wavelength, conformational flexibility, and vibronic coupling on singlet fission. Photoexcitation of the low-energy absorption results in a superposed mixture of states, which transform on an ultrafast time-scale into a spin-correlate...

Cyclic tetraaryl[5]cumulenes (1 a–f) have been synthesized and studied as a function of increasing ring strain. The magnitude of ring strain is approximated by the extent of bending of the cumulenic core as assessed by a combination of X‐ray crystallographic analysis and DFT calculations. Trends are observed in ¹³C NMR, UV‐vis, and Raman spectra as...

Three pentacene dimers have been synthesized to investigate the effect of molecular rotation and rotational conformations on singlet fission (SF). In all three dimers, the pentacene units are linked by a 1,4-diethynylphenylene spacer that provides almost unimpeded rotational freedom between the pentacene- and phenylene-subunits in the parent dimer....

Solution-processed, large-area, and flexible electronics largely relies on the excellent electronic properties of sp$^2$-hybridized carbon molecules, either in the form of $\pi$-conjugated small molecules and polymers or graphene and carbon nanotubes. Carbon with sp-hybridization, the foundation of the elusive allotrope carbyne, offers vast opportu...

Solution‐processed, large‐area, and flexible electronics largely relies on the excellent electronic properties of sp2‐hybridized carbon molecules, either in the form of π‐conjugated small molecules and polymers or graphene and carbon nanotubes. Carbon with sp‐hybridization, the foundation of the elusive allotrope carbyne, offers vast opportunities...

The Friedel‐Crafts acylation of hexaphenylbenzene is reported, and the reaction favorably provides the monoacylated products 1 a and 1 b. The resulting ketones 1 a and 1 b are used as precursors for the formation of [5]cumulenes, including 6 b in which the sterically demanding HPB moiety affords a diethynyl[5]cumulene that features significant stab...

Catalytic iodine in the presence of water acts indirectly as a source of Brønsted acid and, concurrently, generates iodonium ion and hydrogen peroxide, which mediate the final oxidative aromatization step in the multicomponent cyclocondensation of an aromatic amine and two aliphatic aldehyde compounds. The oxidative cycle in this and related iodine...

Asphaltenes comprise the heaviest and least understood fraction of crude petroleum. The asphaltenes are a diverse and complex mixture of organic and organometallic molecules in which most of the molecular constituents are tightly aggregated into more complicated suprastructures. The bulk properties of asphaltenes arise from a broad range of polycyc...

For over four decades, François Diederich was an inspiration in organic, biological, and materials chemistry. His work influenced generations of chemists, and his visions changed many aspects of modern chemistry. With his passing in 2020, we have lost a mentor, a friend, and a wonderful human being. He will be missed by his colleagues, students, fr...

The cover image is based on the Editorial In memoriam—Prof. François Diederich by Rik R. Tykwinski and Michael M. Haley; cover illustration by Annie Tykwinski, https://doi.org/10.1002/poc.4159.

The versatility of carbon is revealed in its all-carbon forms (allotropes), which feature unique properties (consider the differences between diamond, graphite, graphene and fullerenes). Beyond natural sources, there are many opportunities to expand the realm of carbon chemistry through the study of new carbon forms. In this work, the synthesis of...

In contrast to previous work, the synergy between panchromatic absorption and molecular singlet fission (SF) is exploited to optimize solar energy conversion through evaluation of the distance dependence of intramolecular Förster Resonance Energy Transfer (i-FRET) in a series of subphthalocyanines (SubPcs) linked to pentacene dimers (Pnc2s). To pro...

Due its complementary absorptions in the range of 450 and 600 nm, an energy‐donating hexaaryl‐subporphyrazine has been linked to a pentacene dimer, which acts primarily as an energy acceptor and secondarily as a singlet fission enabler. In the corresponding conjugate, efficient intramolecular Förster resonance energy transfer (i‐FRET) is the modus...

The hierarchical synthesis of three porphyrin and four bisporphyrin derivatives is presented. This strategy relies on the incorporation of linkers based on azo moieties appended with pyridyl and/or acetylenic groups that facilitate axial coordination to Ga‐ and Ru‐metalloporphyrins. These porphyrinic systems allow for a quantitative analysis of the...

Aufgrund seiner komplementären Absorptionen im Bereich von 450 bis 600 nm wurde ein energiespendendes Hexaarylsubporphyrazin an ein Pentacendimer gebunden, das hauptsächlich als Energieakzeptor und sekundär als Singulettspaltungsaktivierer fungiert. Im entsprechenden Konjugat ist der effiziente intramolekulare Förster‐Resonanzenergietransfer (i‐FRE...

The Cover Feature highlights the mirror‐image relationship between two enantiomeric dimers used to explore singlet fission (SF) in the presence of a heavy atom. Spectroscopic techniques outline SF through a virtual CT intermediate that is independent of chirality (cover art by Annie Tykwinski; background photo courtesy of James Wheeler on Unsplash)...

The optoelectronic properties of various carbon allotropes and nanomaterials have been well established, while the purely sp-hybridized carbyne remains synthetically inaccessible. Its properties have therefore frequently been extrapolated from those of defined oligomers. Most analyses have, however, focused on the main optical transitions in UV-Vis...

Previous reports in the literature describe that the crystallization of hexaphenyl carbodiphosphorane (CDPPh) from a variety of solvents gives a “bent” geometry for the P–C–P moiety as the solid-state molecular structure. However, a linear structure is observed when CDPPh is crystallized from benzene. Here, we report detailed spectroscopic and theo...

The synthesis of a series of unsymmetrical derivatives of pentacene appended with functionalized anthracene moieties is reported. These anthracene−pentacene dyads have been characterized by UV‐vis spectroscopy and cyclic voltammetry to examine their electronic properties. X‐ray crystallographic analysis was used to examine the solid‐state features...

Singlet fission (SF), that is, producing two triplet excited states (T1+T1) from a single singlet excited state (S1S0), has the potential to surpass the thermodynamic Shockley–Queisser limit for solar cells of 33 %. Of great relevance for singlet fission is the (S1S0)‐to‐¹(T1T1) transformation as it is the key step in driving the efficiency of SF....

Carbyne and linear carbon structures based on sp-hybridization are attractive targets as the ultimate 1D system (i.e., one-atom in diameter) featuring wide tunability of optical and electronic properties.1–3 Two possible structures exist for sp-carbon atomic wires a) the polyynes with alternated single-triple bonds, and b) the cumulenes with contig...

A porphyrazine featuring complementary absorption to a pentacene dimer was chosen to fill the absorption gap of the latter in the range of 450 to 600 nm to realize panchromatic absorption through the visible region out to ca. 700 nm. Of even greater relevance is the quantitative intramolecular Förster resonance energy transfer (i-FRET) to funnel en...

TThe process of singlet fission (SF) produces two excited triplet states (T1+T1) from one excited singlet exciton (S1) and a molecule in its ground state (S0). It, thus, possesses the...

A tetrameric pentacene, PT, has been used to explore the effects of exciton delocalization on singlet fission (SF). For the first time, triplet decorrelation through intramolecular triplet diffusion was observed following SF. Transient absorption spectroscopy was used to examine different decorrelation mechanisms (triplet diffusion versus structura...

Graphyne allotropes of carbon are fascinating materials, and their electronic properties are predicted to rival those of the "wonder material" graphene. One allotrope of graphyne, having rectangular symmetry rather than hexagonal, stands out as particularly attractive, namely 6,6,12-graphyne. It is currently an insurmountable challenge, however, to...

Pentacene shows unique electronic properties that have long been appreciated and exploited. Over the past 20 years, new synthetic schemes have been developed to address some of the problems encountered with pristine pentacene (e.g., stability and solubility), and pentacene derivatives have become a mainstay in the realm of organic semiconductors in...

Nicht zu unterschätzen: Ein tetrameres Pentacen fungierte als Modellsystem, um den Einfluss der Excitonen‐Delokalisierung auf die Singulett‐Spaltung (SF) sowie den von Excitonen‐Diffusion auf die der SF nachfolgende Triplett‐Dekorrelation zu studieren. Experiment und Theorie zeigten die Delokalisierung von Singulett‐ und Triplett‐Excitonen über die...

An aromatic celebration: ChemPlusChem is pleased to publish a Special Issue on Novel Aromatics, guest‐edited by Aiko Fukazawa, Shinji Toyota, Rik Tykwinski, and Wallace Wong. This project is associated with the organizers of the 18th International Symposium on Novel Aromatic Compounds (ISNA‐18), to be held in Sapporo, Japan (July 21–26, 2019). The...

Tailoring synthetic strategies toward complex, but well‐defined, molecular architectures is an important aspect of Today's organic chemistry. Herein, we present designs to build up [3]rotaxanes of Type 2.1 and Type 3 that feature both a polyyne and a cumulene axle in a single mechanically interlocked molecule. The combination of two sp‐hybridized c...

We have designed and used four different spacers to connect two pentacenes and probed the impact of the spacer on the key steps in singlet fission (SF), that is, the 1(S1S0) to 1(T1T1) transition, as well as the 1(T1T1) to 5(T1T1) transition. In terms of 1(S1S0) to 1(T1T1) transition, a super-exchange mechanism, that is, coupling to a higher-lying...

Singlet fission (SF) allows two charges to be generated from the absorption of a single photon and is, therefore, potentially transformative toward improving solar energy conversion. Key to the present study of SF is the design of pentacene dimers featuring a xanthene linker that strictly places two pentacene chromophores in a rigid arrangement and...

Surpassing the Shockley–Queisser limit, which places an upper bound on solar conversion efficiency for a single p–n junction solar cell at slightly more than 30%, is one of the grand challenges in the field of solar-energy research. Singlet fission (SF)in molecular acenes, the molecular analog of multiple exciton generation (MEG), has the potential...

The first example of a new class of carbon‐rich molecules is introduced, namely, a derivative of tetraethynyl[5]cumulene (TE5C). The use of sterically demanding pendent groups is the decisive structural feature to provide a stable product. Whereas triisopropylsilyl groups are seemingly not sufficiently large to afford an isolable cumulene product,...

The chemical reduction of a [3]cumulene ([3]TrTol) has been explored using alkali metals. Mono‐ and doubly reduced forms of [3]TrTol were isolated as solvent‐separated ion pairs with {Na(18‐crown‐6)THF2}⁺ and {K(18‐crown‐6)THF2}⁺ counterions and crystallographically characterized. This allowed analysis of structural parameters of the “naked” anions...

The chemical reduction of a [3]cumulene ([3]TrTol) is explored using alkali metals. Mono‐ and doubly‐reduced forms of [3]TrTol are isolated as solvent‐separated ion pairs (SSIP) with {Na(18‐crown‐6)}+ and {K(18‐crown‐6)THF2}+ counter ions and crystallographically characterized. This allows analysis of structural parameters of the “naked” anions of...

Multidimensional, conjugated building blocks have been formed through the axial coordination of polyynes to the central Ga atom of tetraarylporphyrins. Electron deficient pentafluorophenyl substituents in the meso‐positions provide more stable σ‐acetylide complexes to Ga than analogous structures with tert‐butylphenyl groups. Mono‐, di‐, and triyne...

Multidimensional, conjugated building blocks have been formed through the axial coordination of polyynes to the central gallium atom of tetraarylporphyrins. Electron deficient pentafluorophenyl substituents on the porphyrin provide more stable sigma‐acetylide complexes to gallium than the analogous structures with tert‐butylphenyl groups in the mes...

Intermolecular singlet fission (SF) is an electronically coupled process between two chromophores, where distance dependences are decisive in terms of rates and yields. In the current work, a family of pentacene derivatives featuring different functional groups have been designed, synthesized, and probed with respect to intermolecular SF in the low...

The Hansen solubility parameters (HSPs) of asphaltene model compounds were determined experimentally via solubility testing. For the test, we synthesized various archipelago-type and continental-type molecule model compounds; five were steroid-derived naphthoquinoline compounds, 14 were phenanthrene/pyrene-derived compounds, two were nickel porphyr...

The synergy of panchromatic absorption throughout most of the visible range of the solar spectrum and intramolecular singlet fission (SF) has been realized in a series of conjugates featuring different light harvesting subphthalocyanines (SubPcs) and an energy accepting pentacene dimer (Pnc2). At the focal point was a modular SubPc approach, which...

The synergy of panchromatic absorption throughout most of the visible range of the solar spectrum and intramolecular singlet fission (SF) has been realized in a series of conjugates featuring different light harvesting subphthalocyanines (SubPcs) and an energy accepting pentacene dimer (Pnc2). At the focal point was a modular SubPc approach, which...

A novel pentacene dimer (P2), and a structurally analogous monomer (P1), bearing a carboxylic acid were designed and synthesized for use in n‐type dye‐sensitized solar cells (DSSC). In P2, the triplet excited states that are formed via the rapid, spin‐allowed process singlet fission (SF) were expected to enable carrier multiplication in comparison...

A novel pentacene dimer (P2), and a structurally analogous monomer (P1), bearing a carboxylic acid were designed and synthesized for use in n‐type dye‐sensitized solar cells (DSSC). In P2, the triplet excited states that are formed via the rapid, spin‐allowed process singlet fission (SF) were expected to enable carrier multiplication in comparison...

Dimeric pentacene derivatives have emerged as the system of choice toward exploring the mechanism of intramolecular singlet fission (iSF). The dimeric structure, and in particular the spacer, allows for controlling and tuning the distance, geometric relationship, and electronic coupling between the two pentacene moieties. This Minireview by R. R. T...

Singlet fission (SF) is a process that converts one singlet excited state into two triplet states. The mechanism of SF is still not well understood. Here, we report on the use of a combination of transient absorption and electron paramagnetic resonance spectroscopies in conjunction with theoretical calculations to probe SF in a pentacene dimer link...

Bonding is the fundamental aspect of organic chemistry, yet the magnitude of C=C bonding in [n]cumulenes as a function of increasing chain length has yet to be experimentally verified for derivatives longer than n = 5. The synthesis of a series of apolar and unsymmetrically substituted tetraaryl[n]cumulenes (n = 3, 5, 7, 9) has been developed and r...

We report on the synthesis, photophysical, and electrochemical characterization of a new family of pentacene derivatives, which are applied in n-type dye-sensitized solar cells (DSSCs). As far as the molecular structure of the pentacene is concerned, the synthetic design focuses on cyano acrylic tethered at the 13-position of the pentacene chromoph...

Laser-induced cross-linking of polyynes is successfully hindered when the polyyne is encapsulated as part of a rotaxane and therefore protected by a surrounding macrocycle. When the rotaxane is electrosprayed, however, noncovalent aggregate ions are efficiently formed. Aggregates of considerable size (including more than 50 rotaxane molecules with...

Bonding is the fundamental aspect of organic chemistry, yet the magnitude of C=C bonding in [n]cumulenes as a function of increasing chain length has yet to be experimentally verified for derivatives longer than n = 5. The synthesis of a series of apolar and unsymmetrically substituted tetraaryl[n]cumulenes (n = 3, 5, 7, 9) has been developed and r...

Singlet fission (SF) involves the spontaneous splitting of a photoexcited singlet state into a pair of triplets, and it holds great promise toward the realization of more efficient solar cells. Although the process of SF has been known since the 1960s, debate regarding the underlying mechanism continues to this day, especially for molecular materia...

We have designed a series of molecules and developed synthetic methodology that allows for the inclusion of structural diversity along both the lateral and vertical axes of the basic TCNQ skeleton. In the lateral direction, benzoannulation extends the π-system through (hetero)acene formation, while incorporation of a [3]cumulene increases delocaliz...

In comparison to the omnipresent two- and three-dimensional allotropes of carbon, namely, graphite and diamond (as well as recent entries graphene, carbon nanotubes, and fullerenes), a detailed understanding of the one-dimensional carbon allotrope carbyne is not well established, and even the existence of carbyne has been a matter of controversy ov...

Acenes, heteroacenes, conjugated polycyclic hydrocarbons, and polycyclic aromatic hydrocarbons (collectively referred to in this review as conjugated polycyclic molecules, CPMs) have fascinated chemists since they were first isolated and synthesized in the mid 19th century. Most recently, these compounds have shown significant promise as the active...

When molecular dimers, crystalline films or molecular aggregates absorb a photon to produce a singlet exciton, spin-allowed singlet fission may produce two triplet excitons that can be used to generate two electron-hole pairs, leading to a predicted 1/450% enhancement in maximum solar cell performance. The singlet fission mechanism is still not wel...

Supplementary Figures, Supplementary Methods, Supplementary Tables and Supplementary References

Bisylides of the type R3P=C=PR3, also known as carbodiphosphoranes, are very reactive compounds having numerous unusual and promising properties. The first representatives of this class of formally divalent carbon(0) compounds has already been synthesized over 50 years ago, but aspects of their chemistry and properties remain ambiguous. Herein, we...

The article discusses synthesis of 1-bromopyrene and 1-pyrenecarbaldehyde. Due to the useful photophysical attributes of pyrene, it is a desirable component of many functional materials. Thus, 1-bromopyrene is a key building block for a large portion of the chemical community. The first synthesis of 2 was described in 1937 by Lock, via the brominat...

This chapter highlights some of the recent advances that have been reported for the formation of carbon-rich materials, based on the use of molecules assembled from sp-hybridized carbon, namely acetylenes, polyynes, and cumulenes. Considering materials based on sp-hybridized carbon, the starting point would be carbyne, the carbon allotrope composed...

Oligoynes are archetypical molecular wires due to their 1-D chain of conjugated carbon atoms and ability to transmit charge over long distances by coherent tunneling. However, the stability of the oligoyne can be an issue. Here we address this problem by two stabilization methods, namely sterically shielding endgroups, and rotaxination to produce a...

More efficient light harvesting throughout the whole solar spectrum by introducing third and fourth components offers a new pathway towards development of high efficiency organic solar cells based on polymer/fullerene blends. Recently, dye molecules have been utilized as promising light harvesting photosensitizers in the near–IR region. Herein, we...

The synthesis of non-conjugated, carbon-rich building blocks is described, based on a basic scaffold of triethynylmethanol (TEtM). The substitution of the ethynyl groups can be easily varied (including R3Si, H, Br), and this allows structural tuning for stabilization, synthetic derivatization, and adsorption on Ag(111) or Au(111). X-ray crystallogr...

Solution based perovskite solar cell fabrication typically involves rather complex processing sequences to yield highest performance. While most studies concentrate on the exploration of processing conditions, we have investigated the purity levels of common perovskite precursor solutions and found a number of impurities which are most critically c...

Two new 6,13-disubstituted pentacene derivatives, 1 c and 1 d, with alkyl and triisopropylsilylethynyl substitution have been synthesized and characterized experimentally and computationally. The alkyl substituted 1 c and 1 d represent the first 6-alkyl-substituted pentacene derivative where the fully aromatic species dominates over the correspondi...