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1.
Chemistry ; 2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-32558004

RESUMO

Starting from versatile acridophosphine a concise synthetic route towards a new family of phosphorus-containing polycyclic aromatic hydrocarbons was established. The structural and optoelectronic properties of these compounds were efficiently modulated through derivatization of the phosphorus center. X-ray crystallographic analysis, UV/vis spectroscopic and electrochemical studies supported by DFT calculations identified the considerable potential of these scaffolds for the development of organophosphorus functional materials with tailored properties upon further functionalization.

2.
J Org Chem ; 85(14): 9255-9263, 2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32584036

RESUMO

Control of isomerization of a receptor bearing multiple light-switchable subunits in a confined space is critical for the design of synthetic molecular machines. Toward this goal, a new azacryptand containing three azobenzene subunits has been developed, and its photoisomerization in an aqueous solution has been studied depending on anion coordination and recognition by a larger host-cucurbit[8]uril (CB[8]). The cryptand in its hexaprotonated form shows considerable affinity for fluoride and perchlorate, which in turn affects the isomer distribution of the receptor under UV-light irradiation, stabilizing the isomers of the cryptand with Z-configurations. CB[8] was found to be able to encapsulate the isomers of the cryptand by forming a Matryoshka-type complex. The irradiation of a 10:1 CB[8]-cryptand mixture has led to a selective conversion of the cryptand to the E,E,Z isomer inside CB[8]. It has been demonstrated that the addition of fluoride to the resulted complex induces the release of the cryptand as a major E,E,E isomer, while other studied anions were ineffective in this reaction. To our knowledge, this work presents a first example of a host-controlled photoisomerization of an anion receptor bearing multiple switching azobenzenes that model the function of naturally occurring chaperones.

3.
Chemistry ; 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32497327

RESUMO

Pyrene-based cyclophanes have been synthesized with the aim to realize a bellows-type sensing mechanism for the ratiometric detection of nucleotide concentrations in a buffered aqueous solution. The sensing mechanism involves the encapsulation of a nucleobase between two pyrene rings, which affects the monomer-excimer equilibrium of the receptor in the excited state. The nature of the spacer and its connection pattern to pyrene rings have been varied to achieve high selectivity for ATP. The 1,8-substituted pyrene-based cyclophane with the 2,2'-diaminodiethylamine spacer demonstrates the best selectivity for ATP showing a 50-fold increase in the monomer-excimer emission ratio upon saturation with the nucleotide. The receptor can detect ATP within the biological concentrations range over a wide pH range. NMR and spectroscopic studies have revealed the importance of hydrogen bonding and stacking interactions for achieving a required receptor selectivity. The probe has been successfully applied for the real-time monitoring of creatine kinase activity.

4.
J Org Chem ; 85(12): 7781-7792, 2020 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-32408737

RESUMO

Within the past decade, tetraaryltetrabenzoporphyrins (TATBPs) have gained rising attention due to their potential in various fields of materials science and medicinal chemistry. However, this class of compounds still lacks in structural diversity, especially in the case of low-symmetrical compounds. Herein, mixed condensations were utilized to generate TATBPs with different substituents either in the meso-positions or the periphery of the macrocycle with total yields of 55-58%. The separation of crude mixtures was achieved by feasible chromatographic purification. The influence of symmetry on the electronic properties of TATBPs was studied by optical spectroscopy, electrochemistry, and X-ray diffraction.

5.
Chempluschem ; 85(5): 921-926, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32401434

RESUMO

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 of anthracene-pentacene dyads 1 a-d with H-, F-, Cl-, and Br- substituents on the 9-position of anthracene, and shows that the packing arrangement of anthracene-pentacene derivatives 1 b,d,e are remarkably similar irrespective of the presence of fluoride, bromide or methyl substituents. The pentacene-anthracene dyads have been incorporated into OTFTs to evaluate their semiconducting properties. The pentacene derivative 1 b shows ambipolar behavior using AlOx C14 PA as the gate dielectric (electron and hole mobilities of 7.6 ⋅ 10-3 and 1.6 ⋅ 10-1  cm2 V-1 s-1 ), while performance of all derivatives was poor using p-doped Silicon as the substrate. These studies highlight the importance of thin-film formation over molecular structure.

6.
Chemistry ; 2020 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-32338388

RESUMO

A synthetic route towards a novel hexabenzocoronene-based helical nanographene motif was developed. A hexaphenylbenzene precursor was therefore designed, which cannot undergo, due to steric restrictions, a complete planarization reaction. This precursor was transformed under oxidative cyclodehydrogenation conditions to a π-extended [5]helicene, which was fully characterized including X-ray diffraction analysis.

7.
Chemistry ; 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32096576

RESUMO

Invited for the cover of this issue are the groups of Lungerich and Jux at the Friedrich-Alexander University Erlangen-Nuernberg. The image depicts the synthetic feasibility with a "TATBP tuning shop", which shows the change of the four meso aryl substituents to modify the performance of the molecule. Read the full text of the article at 10.1002/chem.201904718.

8.
Chemistry ; 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31970834

RESUMO

This work reports the design and synthesis of a sterically protected triphenylamine scaffold which undergoes one-electron oxidation to form an amine-centered radical cation of remarkable stability. Several structural adjustments were made to tame the inherent reactivity of the radical cation. First, the parent propeller-shaped triphenylamine was planarized with sterically demanding bridging units and, second, protecting groups were deployed to block the reactive positions. The efficiently shielded triphenylamine core can be reversibly oxidized at moderate potentials (+0.38 V, vs. Fc/Fc+ in CH2 Cl2 ). Spectroelectrochemistry and chemical oxidation studies were employed to monitor the evolution of characteristic photophysical features. To obtain a better understanding of the impact of one-electron oxidation on structural and electronic properties, joint experimental and computational studies were conducted, including X-ray structural analysis, electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. The sterically shielded radical cation combines various desirable attributes: A characteristic and unobstructed absorption in the visible region, high stability which enables storage for weeks without spectroscopically traceable degradation, and a reliable oxidation/re-reduction process due to effective screening of the planarized triphenylamine core from its environment.

9.
Chemistry ; 26(16): 3474-3478, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-31797440

RESUMO

The synthesis and extensive experimental (X-ray crystallography, UV/Vis spectroscopy, cyclic voltammetry) and theoretical (DFT calculations) characterization of two isomeric dithieno[b,f]phosphepines (DTPs) are presented herein. The relative orientation of the phosphepine and the thiophene moieties has a decisive impact on the electronic and structural properties of these compounds. Moreover, the thiophene units allow for a facile subsequent functionalization through direct Pd-catalyzed C-H coupling, which renders DTPs highly promising building blocks for organophosphorus functional materials.

10.
Chemistry ; 26(15): 3287-3296, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-31846109

RESUMO

Tetraaryltetrabenzoporphyrins (TATBPs) show, due to their optoelectronic properties, rising potential as dyes in various fields of physical and biomedical sciences. However, unlike in the case of porphyrins, the potential structural diversity of TATBPs has been explored only to little extent, owed mainly to synthetic hurdles. Herein, we prepared a comprehensive library of 30 TATBPs and investigated their fundamental properties. We elucidated structural properties by X-ray crystallography and found explanations for physical properties such as solubility. Fundamental electronic aspects were studied by optical spectroscopy as well as by electrochemistry and brought in context to the stability of the molecules. Finally, we were able to develop a universal synthetic protocol, utilizing a readily established isoindole synthon, which gives TATBPs in high yields, regardless of the nature of the used arylaldehyde and without meticulous chromatographic purifications steps. This work serves as point of orientation for scientists, that aim to utilize these molecules in materials, nanotechnological, and biomedical applications.

11.
Nat Commun ; 10(1): 3714, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31420550

RESUMO

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 design and execute a synthesis of this material. Herein, we present synthesis and electronic properties of molecules that serve as model compounds. These oligomers, so-called radiaannulenes, are prepared by iterative acetylenic coupling reactions. Systematic optical and redox studies indicate the effective conjugation length of the radiaannulene oligomers is nearly met by the length of the trimer. The HOMO-LUMO gap suggested by the series of oligomers is still, however, higher than that expected for 6,6,12-graphyne from theory, which predicts two nonequivalent distorted Dirac cones (no band gap). Thus, the radiaannulene oligomers present a suitable length in one dimension of a sheet, but should be expanded in the second dimension to provide a unique representation of 6,6,12-graphyne.

12.
Chemistry ; 25(66): 15083-15090, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31429504

RESUMO

Porphyrin-hexabenzocoronene architectures serve as good model compounds to study light-harvesting systems. Herein, the synthesis of porphyrin functionalized hexa-peri-hexabenzocoronenes (HBCs), in which one or more porphyrins are covalently linked to a central HBC core, is presented. A series of hexaphenylbenzenes (HPBs) was prepared and reacted under oxidative coupling conditions. The transformation to the respective HBC derivatives worked well with mono- and tri-porphyrin-substituted HPBs. However, if more porphyrins are attached to the HPB core, Scholl oxidations are hampered or completely suppressed. Hence, a change of the synthetic strategy was necessary to first preform the HBC core, followed by the introduction of the porphyrins. All products were fully characterized, including, if possible, single-crystal XRD. UV/Vis absorption spectra of porphyrin-HBCs showed, depending on the number of porphyrins as well as with respect to the substitution pattern, variations in their spectral features with strong distortions of the porphyrins' B-band.

13.
Nat Commun ; 10(1): 3278, 2019 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332189

RESUMO

The chirality-controlled synthesis of single-walled carbon nanotubes (SWCNTs) is a major challenge facing current nanomaterials science. The surface-assisted bottom-up fabrication from unimolecular CNT seeds (precursors), which unambiguously predefine the chirality of the tube during the growth, appears to be the most promising approach. This strategy opens a venue towards controlled synthesis of CNTs of virtually any possible chirality by applying properly designed precursor molecules. However, synthetic access to the required precursor molecules remains practically unexplored because of their complex structure. Here, we report a general strategy for the synthesis of molecular seeds for the controlled growth of SWCNTs possessing virtually any desired chirality by combinatorial multi-segmental assembly. The suggested combinatorial approach allows facile assembly of complex CNT precursors (with up to 100 carbon atoms immobilized at strictly predefined positions) just in one single step from complementary segments. The feasibility of the approach is demonstrated on the synthesis of the precursor molecules for 21 different SWCNT chiralities utilizing just three relatively simple building blocks.

14.
Angew Chem Int Ed Engl ; 58(43): 15263-15267, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31342607

RESUMO

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 structural changes) for PT and its dimeric equivalent PD on the basis of the rate and activation barrier of the decorrelation step. Charge-separation experiments using tetracyano-p-quinodimethane (TCNQ) to quench triplet excitons formed through SF demonstrate that enhanced intersystem crossing, that is, spin catalysis, is a widely underestimated obstacle to quantitative harvesting of the SF products. The importance of spatial separation of the decorrelated triplet states is emphasized, and independent proof that the decorrelated triplet pair state consists of two (T1 ) states per molecule is provided.

15.
Allergy Asthma Proc ; 40(4): 261-272, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31053180

RESUMO

Background: GSP301 is an investigational fixed-dose combination nasal spray that contains the antihistamine, olopatadine hydrochloride (HCl), and the corticosteroid, mometasone furoate. Objective: To evaluate the efficacy and safety of GSP301 in patients with seasonal allergic rhinitis (SAR). Methods: In this double-blind, randomized, parallel-group study, patients (≥12 years of age) with SAR were equally randomized to intranasal GSP301 (olopatadine 665 µg and mometasone 25 µg), olopatadine HCl (665 µg), mometasone furoate (25 µg), or placebo for 14 days of twice-daily treatment. The primary end point was the mean change from baseline in the average A.M. and P.M. 12-hour reflective Total Nasal Symptom Score (rTNSS) analyzed by using mixed-effect model repeated measures (p < 0.05 indicates statistical significance). Additional assessments included instantaneous TNSS (iTNSS), individual nasal symptoms, reflective Total Ocular Symptom Score (rTOSS) and instantaneous Total Ocular Symptom Score (iTOSS), onset of action, Physician-assessed Nasal Symptom Score (PNSS), quality of life, and adverse events (AE). Results: A total of 1180 patients were randomized. Over 14 days of treatment, GSP301 significantly improved average A.M. and P.M. rTNSS versus placebo (least squares mean difference -0.98 [95% confidence interval, -1.38 to -0.57]; p < 0.001) and versus olopatadine (p = 0.003), and approached statistical significance versus mometasone (p = 0.059). GSP301 also significantly improved average A.M. and P.M. iTNSS versus placebo and both monotherapies (p < 0.05, all). Further, GSP301 significantly improved individual nasal symptoms, overall ocular symptoms (rTOSS and iTOSS), and overall quality of life versus placebo (p < 0.01, all). Onset of action for GSP301 was observed within 15 minutes and was maintained at all subsequent time points assessed. Results for the PNSS also were significant for GSP301 versus placebo (p < 0.001). The percentages of patients with treatment-emergent AEs treated with GSP301, olopatadine, mometasone, and placebo were 12.9, 12.5, 7.1, and 9.4%, respectively. Conclusion: GSP301 was efficacious and well tolerated for the treatment of SAR symptoms compared with placebo, with a rapid onset of action of 15 minutes in patients ≥12 years of age.Clinical trial NCT02631551, www.clinicaltrials.gov.

16.
Org Biomol Chem ; 17(19): 4850-4855, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-31037280

RESUMO

A new protocol for the synthesis of pyrazol-5-ylvinyl ketones, e.g. pyrazole-chalcones, employing furfuryl ketones as a triketone equivalent, has been developed. The reaction occurs under mild conditions and does not require the use of expensive materials. Other important benefits include the simplicity and atom efficiency of this approach.

17.
Dalton Trans ; 48(17): 5800-5816, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30977490

RESUMO

Reaction of (p-tol3P)2PtCl2 and Me3Sn(C[triple bond, length as m-dash]C)2SiMe3 (1 : 1/THF/reflux) gives monosubstituted trans-Cl(p-tol3P)2Pt(C[triple bond, length as m-dash]C)2SiMe3 (63%), which with wet n-Bu4N+ F- yields trans-Cl(p-tol3P)2Pt(C[triple bond, length as m-dash]C)2H (2, 96%). Hay oxidative homocoupling (O2/CuCl/TMEDA) gives all-trans-Cl(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4Pt(Pp-tol3)2Cl (3, 68%). Reaction of 3 and Me3Sn(C[triple bond, length as m-dash]C)2SiMe3 (1 : 1/rt) affords monosubstituted all-trans-Cl(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4Pt(Pp-tol3)2(C[triple bond, length as m-dash]C)2SiMe3 (46%), which is converted by a similar desilylation/homocoupling sequence to all-trans-Cl[(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4]3Pt(Pp-tol3)2Cl (7; 79%). Reaction of (p-tol3P)2PtCl2 and excess H(C[triple bond, length as m-dash]C)2SiMe3 (HNEt2/cat. CuI) gives trans-Me3Si(C[triple bond, length as m-dash]C)2Pt(Pp-tol3)2(C[triple bond, length as m-dash]C)2SiMe3 (78%), which with wet n-Bu4N+ F- affords trans-H(C[triple bond, length as m-dash]C)2Pt(Pp-tol3)2(C[triple bond, length as m-dash]C)2H (96%). Hay oxidative cross coupling with 2 (1 : 4) gives all-trans-Cl[(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4]2Pt(Pp-tol3)2Cl (10, 36%) along with homocoupling product 3 (33%). Reaction of 3 and Me3Sn(C[triple bond, length as m-dash]C)2SiMe3 (1 : 2/rt) yields all-trans-Me3Si(C[triple bond, length as m-dash]C)2(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4Pt(Pp-tol3)2(C[triple bond, length as m-dash]C)2SiMe3 (17, 77%), which with wet n-Bu4N+ F- gives all-trans-H(C[triple bond, length as m-dash]C)2(p-tol3P)2Pt(C[triple bond, length as m-dash]C)4Pt(Pp-tol3)2(C[triple bond, length as m-dash]C)2H (96%). Reaction of 3 and excess Me3P gives all-trans-Cl(Me3P)2Pt(C[triple bond, length as m-dash]C)4Pt(PMe3)2Cl (4, 86%). A model reaction of trans-(p-tol)(p-tol3P)2PtCl and KSAc yields trans-(p-tol)(p-tol3P)2PtSAc (12, 75%). Similar reactions of 3, 7, 10, and 4 give all-trans-AcS[(R3P)2Pt(C[triple bond, length as m-dash]C)4]nPt(PR3)2SAc (76-91%). The crystal structures of 3, 17, and 12 are determined. The first exhibits a chlorine-chlorine distance of 17.42 Å; those in 10 and 7 are estimated as 30.3 Å and 43.1 Å.

18.
Angew Chem Int Ed Engl ; 58(26): 8932-8937, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-30968516

RESUMO

Single-molecule electronic components (SMECs) are envisioned as next-generation building blocks in quantum circuit systems. However, challenges such as the reproducibility of the electrode attachment to the individual molecules hamper their fundamental investigation. For our purpose, we introduced quasi optoelectronic electrodes (QOEs) that allow for rapid investigations of the properties and suitability of compounds for molecular electronic devices. In particular, we probed hexa-peri-hexabenzocoronene (HBC) as a model system for D6h -symmetrical nanographenes, with porphyrins as QOEs attached to the periphery. We prepared selectively bis-porphyrin-functionalized HBCs with ortho-, meta- and para-substitution and studied their communication properties, in correlation to the geometrical alignment and size of the system, by electrochemistry and optical spectroscopy. Further insights into structure-property relationships were gained by DFT calculations and X-ray diffraction analysis.

19.
Chem Sci ; 10(13): 3854-3863, 2019 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-31015927

RESUMO

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, in turn, enforces efficient, intramolecular π-overlap that mimics interactions typically found in condensed state (e.g., solids, films, etc.). Inter-chromophore communication ensures Davydov splitting, which plays an unprecedented role toward achieving SF in pentacene dimers. Transient absorption measurements document that intramolecular SF evolves upon excitation into the lower Davydov bands to form a correlated triplet pair at cryogenic temperature. At room temperature, the two spin-correlated triplets, one per pentacene moiety within the dimers, are electronically coupled to an excimer state. The presented results are transferable to a broad range of acene morphologies including aggregates, crystals, and films.

20.
Allergy Asthma Proc ; 40(3): 162-166, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31018890

RESUMO

Background: Approximately 80% of patients with asthma and chronic obstructive pulmonary disease incorrectly use a metered-dose inhaler and, therefore, fail to obtain full benefit from their inhaler medication. Beclomethasone dipropionate (BDP) hydrofluoroalkane, an inhalation aerosol administered via a breath-actuated inhaler (BAI) has been designed to improve ease of use over press-and-breathe metered-dose inhalers by eliminating the need for hand-breath coordination. Objective: To present the mechanics of the BAI device, assess the minimum reliable inspiratory flow rate required to trigger an actuation, and evaluate if intended users can safely and effectively use the BDP BAI according to the instructions for use (IFU). Methods: Six random batches (three batches each of 40 µg and 80 µg) of 10 inhalers were evaluated for the minimum inspiratory flow rate required for actuation trigger. Each inhaler was tested for actuation at five flow rates: 12, 14, 16, 18, and 20 L/min. Simulated-use testing was conducted with 91 participants from six representative user groups in the United States to assess the use of a placebo-filled production-equivalent BDP BAI according to the IFU. Results: Across the 40-µg batches, 83% of the devices actuated at 16 L/min and 100% actuated at 18 and 20 L/min. For the 80-µg batches, 67% and 100% actuated at 18 L/min and 20 L/min, respectively. All the participants demonstrated successful use of the BDP BAI during the study session. Isolated safety-critical errors with the potential for no-dose delivery were recorded for 15 participants but were considered unrelated to the design of the IFU. Conclusion: The BDP BAI consistently triggered actuation at an airflow rate of 20 L/min and was successfully used based on guidance from the IFU only. This device provides an alternative for patients who find it difficult to use metered-dose inhaler devices correctly.


Assuntos
Antiasmáticos/administração & dosagem , Beclometasona/administração & dosagem , Inaladores Dosimetrados , Administração por Inalação , Asma/tratamento farmacológico , Simulação por Computador , Humanos , Pulmão/fisiopatologia , Taxa Respiratória
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