Dichloromethane Solution Research Articles

Carbazole/triphenylamine-functionalized phenanthro[4,5-abc]phenazines: Synthesis and luminescence properties

Two phenanthro[4,5-abc]phenazine derivatives, 11-(3,6-di‑tert‑butyl‑9H-carbazol-9-yl)phenanthro[4,5-abc]phenazine (PyQ-Cz) and 4-(phenanthro[4,5-abc]phenazin-11-yl)-N,N-diphenylaniline (PyQ-TPA), were synthesized by grafting the an electron-donating carbazole and triphenylamine segments onto the pyrene-fused quinoxaline (PyQ) core, respectively and characterized by NMR (1H and 13C) and high resolution mass spectrometry. Their thermal, photophysical and electrochemical properties were systematically investigated. These compounds exhibited excellent thermal stability and intense yellow emission and orange emission in dichloromethane solution, whereas they exhibited green emission in solid films. Based on their high photoluminescence quantum yields and the frontier orbital energies, the doped devices with a structure of ITO/PEDOT:PSS (30 nm)/CBP:PyQ derivatives (x wt%) (25 nm)/TPBi (35 nm)/Liq (2 nm)/Al (150 nm) were fabricated by solution-processed the emitting layers to investigate their electroluminescence (EL) performances, in which the doped devices of PyQ-Cz exhibited the maximum external quantum efficiency (EQEmax) of 1.86 %, while the PyQ-TPA doped devices showed an EQEmax of 0.82 %.

Synthesis of octa-benzothiazole functionalized tetraphenylethylene and their explosive sensing properties

The detection of nitroaromatic compounds (NACs) such as 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) is critical for environmental monitoring and security, due to their extensive use in explosives and the associated health risks. However, current methods for detecting these compounds face challenges in sensitivity, specificity, and practicality. In this study, a new benzothiazole functionalized tetraphenylethylene molecular scaffold (TPE-BTH) have been successfully synthesized and characterized for its potential in explosive sensing. The TPE-BTH compound exhibits distinct UV–Visible and fluorescence emission behaviors in different solvent polarities. A remarkable feature of TPE-BTH is its pronounced fluorescence quenching upon the addition of 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) in a dichloromethane solution, highlighting its sensitivity and potential utility in explosive detection. The detection limits for TNP and DNP were determined to be remarkably low at 7.28 × 10-8 M and 1.23 × 10-8 M, respectively. Through theoretical investigations, we explored the interaction mechanisms between TPE-BTH and TNP, uncovering the roles of internal hydrogen bonding within picric acid and π-π interactions as well as dipole interactions between the molecules. Additionally, 1H NMR was utilized to elucidate the interaction mechanisms between TPE-BTH and TNP. The development of TPE-BTH as a molecular scaffold for NAC detection significantly contributes to the field of explosive sensing and environmental monitoring.

Synthesis of random copolymers of styrene and arylamino substituted styrenes and their sensitivities towards nitroaromatics

AbstractRandom copolymers of styrene and substituted styrenes bearing arylamino substituents as fluorophore units have been obtained. Their photophysical properties have been investigated by measuring absorption and emission spectra as in solutions as solid‐state. All copolymers proved to possess absolute quantum yields up to 0.39 in solution and up to 0.05 in solid‐state, depending on their fluorophore substituents. Fluorescence studies have shown that these copolymers show a highly sensitive response towards a diversity of nitroaromatic compounds, both in solutions and in a vapor phase. The detection limits for these compounds towards model nitroaromatic explosives in dichloromethane solution proved to be in the range from 10−6 to 10−7 mol/L. The fluorescent materials prepared by electrospinning of synthesized copolymers have been evaluated as sensor materials for detecting nitrobenzene vapor for our hand‐made sniffer with detection limits of 0.5 ppm during 100‐s exposure to the vapor.

A series of 2‐phenylbenzothiazole‐based iridium complexes with N‐H derivatives: synthesis, photophysics, DFT calculations and a preliminary exploration in fluoride ions sensing

AbstractA series of new pbt‐based Ir(III) complexes containing N−H derivatives ancillary ligands (piz/pbiz) were designed and synthesized rationally, naming [(CH3Opbt)2Ir(piz)][PF6] (Ir1), [(CF3pbt)2Ir(piz)][PF6] (Ir2), [(Fpbt)2Ir(piz)][PF6] (Ir3), [(CH3Opbt)2Ir(pbiz)][PF6] (Ir4), [(CF3pbt)2Ir(pbiz)][PF6] (Ir5) and [(Fpbt)2Ir(pbiz)][PF6] (Ir6) (where pbt=2‐phenylbenzothiazole, piz=2‐(1H‐imidazol‐2‐yl)pyridine, and pbiz=2‐(pyridin‐2‐yl)‐1H‐benzoimidazole). Combined with photophysical properties and theoretical calculations, their structure‐property relationships were systematically researched. These iridium(III) complexes are phosphorescent in the green and yellow‐green region with quantum yields of 14.1–28.7 % and lifetimes of 0.35–0.88 μs. Considering the relatively high quantum yield and imidazole group on ancillary ligands, [(CF3pbt)2Ir(pbiz)][PF6] (Ir5) was preliminary explored as the phosphorescent sensor toward F− ions. The results showed that the addition of fluoride ions to complex Ir5 in dichloromethane solution induced a red shift of the emission color, along with an enhancement in the luminescent intensity. Theoretical calculations were carried out to understand the mechanism, and the results reveal that the hydrogen bonding interaction of N−H bond with F− influence the electron transfer processes of the lowest energy absorption and emission, leading to a significant change in the photophysical properties.

Synthesis and Photophysical Evaluation of Isoleptic Pt(II) and Pd(II) Complexes Utilizing N^N^N Ligands as Luminophoric Chelators with Different Ancillary Ligands

We herein report on the synthesis and structural characterization, as well as on the photophysical properties, of a series of isoleptic Pt(II) and Pd(II) complexes featuring tridentate N^N^N chelators as luminophores while bearing diverse ancillary co-ligands. Six new palladium complexes were synthesized using 2,6-bis(3-(tert-butyl/trifluoromethyl)-1H-1,2,4-triazol-5-yl)pyridine (tbu or CF3, respectively) in combination with four distinct ancillary ligands, namely: 4-amylpyridine (AmPy), 2,6-dimethylphenyl isonitrile (CNR), triphenylphosphane (PPh3), and 1,3,5-triaza-7-phosphaadamantane (PTA). Thus, two novel Pt(II) complexes incorporating the co-ligands CNR and PTA were explored. The remaining platinum-based complexes, namely CF3-Pt-AmPy, tbu-Pt-AmPy, CF3-Pt-PPh3, and tbu-Pt-PPh3, were re-synthesized according to our previous work for a systematic comparison with their Pd(II) homologues. Thus, photophysical studies were performed in different solvents and conditions. The Pt(II) complexes demonstrated comparable or superior photophysical characteristics in toluene when compared with their solutions in liquid dichloromethane at room temperature. In contrast, the Pd(II) complexes exhibited no significant photoluminescence in dichloromethane, but a surprisingly clear emission was observed for tbu-Pd-AmPy, tbu-Pd-CNR, and tbu-Pd-PPh3 in liquid toluene at room temperature. The significant differences regarding excited state lifetimes and photoluminescence quantum yields underscore the impact of solvent selection on photophysical characteristics, emphasizing the need to consider metal-ligand interactions, as well as the surrounding microenvironment, for a comprehensive interpretation of their photophysical properties. In addition, it is clear that AmPy and CNR render better luminescence efficiencies, whereas PTA is only suitable in toluene.

Organic Polar Crystals, Second Harmonic Generation, and Piezoelectric Effects from Heteroadamantanes in the Space Group R3m.

Polar crystalline materials, a subset of the non-centrosymmetric materials, are highly sought after. Their symmetry properties make them pyroelectric and also piezoelectric and capable of second-harmonic generation (SHG). For SHG and piezoelectric applications, metal oxides are commonly used. The advantages of oxides are durability and hardness - downsides are the need for high-temperature synthesis/processing and often the need to include toxic metals. Organic polar crystals, on the other hand, can avoid toxic metals and can be amenable to solution-state processing. While the vast majority of polar organic molecules crystallize in non-polar space groups, we found that both 7-chloro-1,3,5-triazaadamantane, for short Cl-TAA, and also the related Br-TAA (but not I-TAA) form polar crystals in the space group R3m, easily obtained from dichloromethane solution. Measurements confirm piezoelectric and SHG properties for Cl-TAA and Br-TAA. When the two species are crystallized together, solid solutions form, suggesting that properties of future materials can be tuned continuously.

Facile Synthesis of High Molecular Weight Poly(ethylene glycol)-b-poly(amino acid)s by Relay Polymerization.

Poly(amino acid)s (PAAs) are one kind of favorable biopolymer that can be used as a drug or gene carrier. However, conventional ring-opening polymerization of PAAs is slow and needs a strict anhydrous environment with an anhydrous reagent as well as the product without enough high molecular weight (Mn), which limits the expanding of PAAs' application. Herein, we took BLG-NCA as the monomer to quickly synthesize one kind of high Mn amphiphilic copolymer, poly(ethylene glycol)-b-poly(γ-benzyl-l-glutamic acid) (PEG-PBLG), by relay polymerization with a simple one-pot method within 3 h in mild conditions (open air, moisture insensitive). In the polymerization process, ring-opening polymerization-induced self-assembly in sodium bicarbonate aqueous solution first occurred to obtain low Mn PEG-PBLG seeds without purification. Then γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA) dichloromethane solution was added into PEG-PBLG seeds directly and stirred vigorously to form am emulsion; during this process, the amphiphilic PEG-PBLG seeds will anchor on the interface of DCM and water to ensure the concentration of α-helix rigid PBLG in DCM to maintain the following relay polymerization. Then, high Mn PEG-PBLG was obtained in mild conditions in one pot. We found that the α-helix rigid structure was essential for relay polymerization by studying the synthetic speed of amphiphilic copolymer with different secondary structures. MOE simulation results showed that PBLG and BLG-NCA tended to form a double hydrogen bond, which was beneficial to relay polymerization because of higher local concentrations that can produce more double hydrogen bonds. Our strategy can quickly obtain high Mn PEG-PBLG (224.9 KDa) within 3 h from PEG-NH2 and BLG-NCA in one pot and did not need an extra initiator. After deprotection, the poly(ethylene glycol)-b-poly(l-glutamate acid) (PEG-PGA) with high Mn as a second product can be used as an excellent antitumor drug carrier. The high Mn PEG-PGA can achieve an encapsulation rate of 86.7% and a drug loading rate of 47.3%, which is twice that of the low Mn PEG-PGA. As a result, the synthesis of PEG-PBLG by relay polymerization simplified the process of PEG-PAA polymerization and increased the Mn. In addition, this method opened a way to obtain other kinds of high Mn PEG-PBLG values in the future.

Enhancing Fluorescence in Both Solution and Solid States Induced by Imine Cage Formation.

Developing luminescent materials that exhibit strong emissions in both solution and solid phases is highly desirable and challenging. Herein, we report imine-bond directed formation of a rigid organic cage (TPE-cage) that was synthesized by [2+4] imine condensation of a TPE-cored tetra-aldehyde (TPE-TA) with a clip-like diamine (XA) to illustrate confinement-induced fluorescence enhancement. Compared to the non-emissive TPE-TA (ϕF =0.26 %) in the dichloromethane (DCM) solution, the TPE-cage achieved a remarkable (~520-fold) emission enhancement (ϕF =70.38 %). In contrast, a monomeric tetra-imine model compound (TPE-model) showed only a minor enhancement (ϕF =0.56 %) in emission compared to the parent tetra-aldehyde TPE-TA. The emission of TPE-cage was further enhanced by ~1.5-fold (ϕF =80.96 %) in the aggregated state owing to aggregation-induced emission enhancement (AIEE). This approach establishes the potential for synthesizing luminescent materials with high emission in both solution and solid-state by employing a single-step imine condensation reaction.

Cooperative intra- and intermolecular hydrogen bonding in scaffolded squaramide arrays.

The structural, self-assembly and binding properties of oligo-(phenylene-ethynylene) (OPE) rigid rods linked to squaramides (SQs) have been studied and correlated with rod length. In the solid-state, OPE-SQ conjugates form indefinite arrays of head-to-tail hydrogen bonded SQs, arrays that include both intra- and intermolecular hydrogen bonds. In dichloromethane solution, intramolecularly hydrogen bonded SQ chains show cooperative polarisation, an effect that increases with OPE-SQ length. Appending powerful hydrogen bonding groups to the OPE-SQ termini further increases this intramolecular polarisation. Greater end-to-end polarisation leads to stronger intermolecular interactions, with longer OPE-SQs showing stronger hydrogen bonding to DMSO as well as stronger self-association. These studies show how cooperative hydrogen bond polarisation in a hydrogen bonded array can be strengthened and how this polarisation can continue intermolecularly.

Side group dependent room temperature crystallization-induced phosphorescence of benzil based all organic phosphors.

In this work, we report alkoxy substituted benzil based all organic room temperature phosphors which showed crystallization induced phosphorescence (CIP). Nine title compounds were prepared with various alkyl lengths (OCnH2n+1: n = 8-16) and the effect of alkyl side group length on the phosphorescence performance was investigated, as compared to p-anisil. It was found that both phosphorescence quantum yield and lifetime increased concomitantly as the alkyl length increased up to nonyloxy (BZL-OC9). Further increase in the carbon number caused the phosphorescence performance to deteriorate due to greater conformational freedom of the side groups. An incredible quantum yield of 70% was achieved for BZL-OC9. A promising finding is that the increased quantum yield was accompanied by the increase in the lifetime relative to p-anisil, which has been historically challenging. Single crystallography coupled with UV-Vis spectroscopy revealed that a higher level of intermolecular π-π interactions was observed from p-anisil while more alkyl interactions with less intermolecular π-orbital overlap were found for BZL-OC8. As a result, molecular rigidification with less phosphorescence quenching was achieved for BZL-OC8 leading to enhanced performance. A precipitation study on a dichloromethane solution as a function of the content of MeOH (poor solvent) proved that the emission of the BZL-OCn system is truly aggregation-induced. The current work demonstrates that strategic side group engineering could be a promising approach to developing high-performance all organic phosphors as well as improving the properties of existing phosphors.

The interplay of chromophore-spacer length in light-induced gold nanocluster self-assembly.

The light-induced self-assembly of chromophore-tethered precision nanoclusters (NCs) has recently received significant attention due to their facile control over structure, function, and reversibility under ambient conditions. However, the magnitude of assembly depends on the photoswitching efficiency, chemical structure, and proximity of the chromophore to the NC surface. Herein, using azobenzene alkyl monothiol (AMT)-capped gold NCs with two different spacer lengths (denoted as C3-NC and C9-NC), we show that reversible cis ↔ trans isomerization efficiency can be readily tuned to control the self-assembly kinetics of NCs. Irrespective of the chain length, the time required for trans-to-cis (140 s) and cis-to-trans (260 s) isomerization of individual C3-AMT and C9-AMT is identical in dichloromethane solution. When a similar experiment was performed using a solution of C3-NCs and C9-NCs, it resulted in self-assembled disc-like superstructures. Notably, the trans-to-cis photoswitching in C3-NC could reach only 65% even after 460 seconds of irradiation. On the other hand, C9-NC completed this process within 160 seconds of irradiation. The low photoswitching efficiency of the C3-NC analog is due to the short and rigid spacer length of C3-AMT ligands, which are in close proximity to the NC surface, resulting in steric hindrance experienced at the NC-chromophore interface. Importantly, the slow photoswitching in C3-NCs helps isolate and investigate the intermediates of assembly. Using high-resolution electron microscopy, atomic force microscopy, and 3D reconstruction, we show that the discs are made up of densely packed arrays of NCs. The prolonged illumination of C9-NCs results in a chain-like assembly due to the dipolar attraction between the previously assembled superstructures. The efficient photoisomerization of chromophores located away from the nanocluster surface has been identified as the key element to speed up the light-induced assembly in chromophore-tethered nanoclusters. Such information will be useful while developing nanoscale photoswitches for electrochemistry, biosensors, and electronic devices.

Development of ruthenium complexes with S-donor ligands for application in synthesis, catalytic acceptorless alcohol dehydrogenation and crossed-aldol condensation.

The reaction of [Ru(dmso)4Cl2] with a potassium salt of four xanthate (RO-C(S)S-; R = Me, Et, iPr and tBu) ligands (depicted as Ln; n = 1-4) in hot methanol afforded a group of mixed-ligand complexes of type [Ru(Ln)2(dmso)2]. The crystal structures of all the four complexes have been determined, which show that the xanthate ligands are bound to the metal center forming four-membered chelates and dmso is coordinated through sulfur and they are mutually cis. The relative thermodynamic stability of this cis and the other possible trans-isomers of these complexes has been assessed with the help of DFT calculations, which have revealed that the cis-isomer is the more stable isomer. The coordinated dmso in the [Ru(Ln)2(dmso)2] complexes could be easily displaced by chelating bidentate ligands (depicted as L') to furnish complexes of type [Ru(Ln)2(L')], as demonstrated through isolation of two such complexes, viz. [Ru(L3)2(bpy)] and [Ru(L2)2(phen)] (bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline). The crystal structure of [Ru(L3)2(bpy)] has been determined and the structure of [Ru(L2)2(phen)] has been optimized by the DFT method. The electronic spectra of the four [Ru(Ln)2(dmso)2] complexes and the two derivatives ([Ru(Ln)2(L')]; n = 3, L' = bpy; n = 2, L' = phen), recorded in dichloromethane solutions, show intense absorptions spanning the visible and ultraviolet regions, which have been analyzed by the TDDFT method. The [Ru(Ln)2(dmso)2] complexes are found to serve as efficient catalyst precursors for the acceptorless dehydrogenation of 2-propanol followed by crossed-aldol condensation with substituted benzaldehydes (and related aldehydes), using tert-butoxide as the co-catalyst, producing dibenzylideneacetone derivatives in good yields.

Dinuclear enantiopure Ln3+ complexes with (S-) and (R-) 2-phenylbutyrate ligands. Luminescence, CPL and magnetic properties.

The reaction of Ln(NO3)2·6H2O (Ln = Nd, Sm, Eu, Tb, Dy, Tm and Yb) with the respective enantiopure (R)-(-)-2-phenylbutyric or (S)-(+)-2-phenylbutyric acid (R/S-2-HPhBut) and 4,7-diphenyl-1,10-phenanthroline (Bphen) allows the isolation of chiral dinuclear compounds of the formula [Ln2(μ-R/S-2-PhBut)4(R/S-2PhBut)2(Bphen)2] where Ln = Nd3+ (R/S-Nd-a), Sm3+ (R/S-Sm-a), Eu3+ (R/S-Eu-a), Tb3+ (R/S-Tb-a and R/S-Tb-b), Dy3+ (R/S-Dy-a and R/S-Dy-b), Tm3+ (R/S-Tm-b) and Yb3+ (R/S-Yb-b). Single crystal X-ray diffraction was performed for compounds S-Eu-a and S-Tm-b. Powder crystal X-ray diffraction was performed for all complexes. From the crystallographic data two different structural motifs were found which are referred to as structure type a and structure type b. In structure type a, the Ln3+ atoms are bridged through four R or S-2-PhBut ligands with two different kinds of coordination modes whereas in structure type b the two Ln3+ atoms are bridged through four R or S-2-PhBut ligands showing only one kind of coordination mode. For those lanthanide ions exhibiting both structure types, Tb3+ and Dy3+, a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu3+ and Tb3+ analogues. Circular Dichroism (CD) and Circular Polarized Luminescence (CPL) in the solid state and in 1 mM dichloromethane (DCM) solutions are reported, leading to improved chiroptical properties for the DCM solutions. The asymmetry factor (glum) in 1 mM DCM is ±0.02 (+ for R-Eu-a) for the magnetically allowed transition 5D0 → 7F1 and ±0.03 (+ for R-Tb-a and R-Tb-b) for the 5D4 → 7F5 transition. Magnetic properties of all compounds were studied and the Dy3+ compound with the structural motif b (R-Dy-b) shows Single Molecular Magnet (SMM) behavior under a 0 T magnetic field. However, R-Dy-a is a field-induced SMM.

Interplay between anion-receptor and anion-solvent interactions in halide receptor complexes characterized with ultrafast infrared spectroscopies.

The competition between host-guest binding and solvent interactions is a crucial factor in determining the binding affinities and selectivity of molecular receptor species. The interplay between these competing interactions, however, have been difficult to disentangle. In particular, the development of molecular-level descriptions of solute-solvent interactions remains a grand experimental challenge. Herein, we investigate the prototypical halide receptor meso-octamethylcalix[4]pyrrole (OMCP) complexed with either chloride or bromide anions in both dichloromethane (DCM) and chloroform (trichloromethane, TCM) solvent using ultrafast infrared transient absorption and 2D IR spectroscopies. OMCP·Br- complexes in both solvents display slower vibrational relaxation dynamics of the OMCP pyrrole NH stretches, consistent with weaker H-bonding interactions with OMCP compared to chloride and less efficient intermolecular relaxation to the solvent. Further, OMCP·Br- complexes show nearly static spectral diffusion dynamics compared to OMCP·Cl-, indicating larger structural fluctuations occur within chloride complexes. Importantly, distinct differences in the vibrational spectra and dynamics are observed between DCM and TCM solutions. The data are consistent with stronger and more perturbative solvent effects in TCM compared to DCM, despite DCM's larger dielectric constant and smaller reported OMCP·X- binding affinities. These differences are attributed to the presence of weak H-bond interactions between halides and TCM, in addition to competing interactions from the bulky tetrabutylammonium countercation. The data provide important experimental benchmarks for quantifying the role of solvent and countercation interactions in anion host-guest complexes.

Phenanthroimidazole-functionalized coumarins: Synthesis and luminescence

Four phenanthroimidazole-functionalized coumarins (C-PI-Bu, C-PI-CN, C-PI-TRZ, and C-PI-Cz) containing a 7-diethylaminocoumarin unit and a phenanthroimidazole (PI) unit with different phenyl substituent at the N1-position, were successfully synthesized and characterized by NMR (1H and 13C), high-resolution mass spectrometry and elemental analysis. The structure-property relationships of the compounds were revealed by systematically investigating their thermal stability, photophysical and electrochemical properties. All four compounds exhibit bright blue-green emission with high fluorescence quantum yield (75.36 %–97.00 %) in dichloromethane solution and green emission in the solid-state. The organic light-emitting diodes (OLEDs) with a device of ITO/PEDOT:PSS (30 nm)/TBADN:coumarin derivative (x, wt%) (25 nm)/TPBi (35 nm)/Liq (2 nm)/Al (150 nm) were fabricated and characterized. The above OLEDs showed the best EL performances with a maximum brightness (Lmax) of 8500 cd/m2, a maximum current efficiency (CEmax) of 3.45 cd/A, and a maximum external quantum efficiency (EQEmax) of 1.30 %.

Synthesis and luminescence properties of V-shaped bis-coumarins with the benzophenone-imbedded triptycene and carbazole

Two new V-shaped bis-coumarins (VBC) with the benzophenone-imbedded triptycene and carbazole, VBCCO-TTC and VBCCOCz, were synthesized and characterized by NMR (1H and 13C), high resolution mass spectrometry and elemental analysis, and their thermal stabilities and photophysical and electrochemical properties were systematically studied. They exhibited strong green emission with high fluorescence quantum yield of 90.4 % and 93.65 % in dichloromethane solution, respectively. The combination of theoretical research and experimental data revealed the structure-property relationship of the functional groups grafted onto the V-shaped bis-coumarins. Moreover, the doped devices treated with the blend of CBP:VBC derivatives as the emitting layers showed green emission, in which the VBCCOCz doped devices exhibited an maximum external quantum efficiency (EQEmax) of 2.66 %, while the VBCCO-TTC doped devices showed an EQEmax of 1.79 %, at the doping concentration of 5 wt%.

Kinetic model-aided process optimization via integrated in-situ FTIR and real-time oscillatory shear rheometry: A case study on impurity control and gelation mitigation for a solid phase peptide cleavage process

Solid phase peptide synthesis is a widely used technique for the production of medicinal peptides, particularly when using unnatural amino acids. In such processes, when the synthesis is complete and the designed peptide sequence is obtained, a subsequent peptide isolation technique is often employed using a trifluoroacetic acid (TFA)/dichloromethane (DCM) solution mixture to promote the cleavage of the peptide from the resin while retaining the protecting groups on the peptide (soft cleavage). The peptide is then isolated via distillation, precipitation/crystallization, and drying unit operations. Throughout these processes, the reaction conditions must be optimized to minimize peptide degradation in the acidic cleavage solution. Furthermore, any peptide network formation during cleavage can dramatically increase the solution viscosity which poses significant operating risks in manufacturing. In this study, a systematic model-aided kinetics and rheology analysis is performed to rapidly identify optimal reaction conditions using the minimum number of screening experiments. The reaction kinetics investigation was conducted with the aid of a mid-FTIR probe to track peptide and TFA solution concentrations during the reaction in real-time. A detailed kinetics model of peptide cleavage and impurity formation is proposed and the adsorption isotherm of TFA is also considered. To confirm that an acceptable solution viscosity can be maintained at the specified reaction conditions over the duration of the projected process time, in-situ oscillatory rheometry was conducted to monitor any viscosity and modulus increase in the soft-cleavage reaction medium. The novel combination of reaction kinetics modeling, impurity control techniques, and the development of a peptide network phase diagram provides a layered approach that can be utilized in the rapid rational design of any solid phase peptide isolation processes.

Efficient Method for the Preparation of Ozonides Under Dry Conditions

Abstract An efficient method for the preparation of ozonides via the reaction of alkenes and ozone under dry conditions is described. The influx of a pre-dried ozone stream into a dichloromethane solution of the olefinic substrates in the presence of molecular sieve 4Å afforded the corresponding ozonides in good to high yields. The reaction in the absence of a molecular sieve gave poor results. The structure of the ozonide was unambiguously confirmed by XRD analysis.

Antifungal activities of leaf extracts from the Capsicum genus

The emergence of microorganisms resistant to antimicrobials has driven the search for new substances aimed at the control and prevention of pathogens. Plant antimicrobial peptides have biotechnological applications in the development of drugs and agricultural inputs for this purpose. The present work aims to evaluate the antifungal activity of extracts containing peptides obtained from the leaves of Capsicum plants. The accessions UENF 1626, 1632 and 1381 and the cultivar Carioquinha were used. The leaves were macerated, and then extraction was performed using a 60% methanol and dichloromethane solution in a 1:1 ratio. The hydromethanolic phase was separated and used for testing after evaporation of methanol. All extracts have a similar electrophoretic profile on tricine gel stained with Coomassie Blue, showing 2 bands of approximately 6.5 and 3.5 kDa. Inhibition of fungal growth with 24 h of culture was performed in liquid culture medium in 96-well plates with reading at 620 nm using extracts with a protein concentration of 200 mg mL-1. The filamentous fungi Fusarium solani, Fusarium lateritium, and Colletotrichum lindemuthianum and the yeasts Candida albicans, Candida buinensis, Candida tropicalis, Saccharomyces cerevisiae, Pichia membranifaciens and Kluyveromyces marxianus were used. The extract with the greatest antifungal potential was the leaves of Capsicum annuum cv. Carioquinha, inhibiting the growth of F. solani by 29%, C. lindemuthianum by 15%, Candida buinensis by 22% and K. marxianus by 24%. Therefore, the extract has peptides with biotechnological potential.

Synthesis, Structure, and Photophysical Properties of Platinum Compounds with Thiophene-Derived Cyclohexyl Diimine Ligands.

Platinum(II) and platinum(IV) compounds were prepared by the stereoselective and regioselective reactions of thiophene-derived cyclohexyl diimine C^N^N-ligands with [Pt2Me4(μ-SMe2)2]. Newly synthesized ligands were characterized by NMR spectroscopy and elemental analysis, and Pt(II)/Pt(IV) compounds were characterized by NMR spectroscopy, elemental analysis, high-resolution mass spectrometry, and single-crystal X-ray diffraction. UV-vis absorbance and photoluminescence measurements were performed on newly synthesized complexes, as well as structurally related Pt(II)/Pt(IV) compounds with benzene-derived cyclohexyl diimine ligands, in dichloromethane solution, as solids, and as 5% by weight PMMA-doped films. DFT and TD-DFT calculations were performed, and the results were compared with the observed spectroscopic properties of the newly synthesized complexes. X-ray total scattering measurements and real space pair distribution function analysis were performed on the synthesized complexes to examine the local- and intermediate-range atomic structures of the emissive solid states.