Positive and negative‐mode laser desorption/ionization‐mass spectrometry (LDI‐MS) for the detection of indigoids in archaeological purple

Laser‐based ionization techniques have demonstrated to be a valuable analytical tool to study organic pigments by mass spectrometric analyses. Though laser‐based ionization techniques have identified several natural and synthetic organic dyes and pigments, they have never been used in the characterization of purple. In this work, positive and negative‐mode laser desorption/ionization mass spectrometry (LDI‐MS) was used for the first time to detect indigoids in shellfish purple. The method was used to study organic residues collected from archaeological ceramic fragments that were known to contain purple, as determined by a classical high‐performance liquid chromatography‐based procedure. LDI‐MS provides a mass spectral fingerprint of shellfish purple, and it was found to be a rapid and successful tool for the identification of purple. In addition, a comparison between positive and negative mode ionization highlighted the complementarity of the two ionization modes. On the one hand, the negative‐ion mode LDI‐MS showed a better selectivity and sensitivity to brominated molecules, such as 6,6'‐dibromoindigo, 6‐monobromoindigo, 6,6'‐dibromoindirubin, 6‐ and 6’‐monobromoindirubin, thanks to their electronegativity, and produced simpler mass spectra. On the other hand, negative‐ion mode LDI‐MS was found to have a lower sensitivity to non‐brominated compounds, such as indigo and indirubin, whose presence can be established in any case by collecting the complementary positive‐ion LDI mass spectrum. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and Properties of Brominated 6,6'-Dimethyl-[2,2'-bi-1H-indene]-3,3'-diethyl-3,3'-dihydroxy-1,1 '-diones

Photochromic 6‐bromomethyl‐6′‐methyl‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 2 ), 6,6′‐ bis(bromomethyl)‐[2,2′‐bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 3 ) and 6,6′‐bis(dibromomethyl)‐[2,2′‐ bi‐1H‐indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 4 ) have been synthesized from 6,6′‐dimethyl‐[2,2′‐bi‐1H‐ indene]‐3,3′‐diethyl‐3,3′‐dihydroxy‐1,1′‐dione ( 1 ). The single crystal of 4 was obtained and its crystal structure was analyzed. The results indicate that in crystal 4 , molecular arrangement is defective tightness compared with its precursor 1 . Besides, UV‐Vis absorption spectra in CH₂Cl₂ solution, photochromic and photomagnetic properties in solid state of 2 , 3 and 4 were also investigated. The results demonstrate that when the hydrogen atoms in the methyl group on the benzene rings of biindenylidenedione were substituted by bromines, its properties could be affected considerably.     

New Chiral Ligand N—Toluenesulfony1—2,2‘—dimethoxy—6,6’—di—aminobiphenyl for Catalytic Asymmetric Transfer Hydrogenation of Ketones

A new chiral ligand N‐p‐toluenesulfonyl‐2,2′‐dimethoxy‐6,6′‐diaminobiphenyl (Ts‐DMBDPPA) was prepared from 2,2′‐dimethoxy‐6,6′‐diaminobiphenyl via N‐tosylation. Its Ru(II) complex was effective catalysts for catalytic asymmetric transfer hydrogenation of aromatic ketones (with ee's up to 69.3%).     

Reactions of 6-hydrazino-, 6-hydroxylaminopurines and related derivatives

7H-Tetrazolo[5,1-i]purine was prepared by nitrosation of 6-hydrazinopurine and by reaction of 6-chloropurine with sodium azide; it was converted to adenine upon catalytic hydrogenation. 6-Hydroxylaminopurine was oxidized to 6-nitrosopurine with manganese dioxide, while alkaline treatment of the former gave 6,6′-azoxypurine. Nitrosation of 6-hydroxylaminopurine afforded 6-(N-nitroso)hydroxylaminopurine. Reaction of 6-chloropurine with 6-hydrazinopurine led to 6,6′-bisadenine; the corresponding ribosyl derivatives gave 6,6′-bisadenosine. Upon air oxidation, 6,6′-bisadenine was converted into 6,6′-azopurine. The related 6-thiosemicarbazino- and 6-(N-methyl)ureidopurine derivatives are also described. 6-N-(Nitroso)hydroxylaminopurine showed an inhibitory activity against several mouse tumors and leukemias.     

A ter­phenyl halide series: 2,6‐Trip2­H3C6X (Trip = 2,4,6‐triiso­propyl­phenyl; X = Cl,Br, I)

The sterically encumbered ter­phenyl halides 2′‐chloro‐2,2′′,4,4′′,6,6′′‐hexaisopropyl‐1,1′:3′,1′′‐terphenyl, C₃₆H₄₉Cl, (I), 2′‐bromo‐2,2′′,4,4′′,6,6′′‐hexaisopropyl‐1,1′:3′,1′′‐terphenyl, C₃₆H₄₉Br, (II), and 2′‐iodo‐2,2′′,4,4′′,6,6′′‐hexaisopropyl‐1,1′:3′,1′′‐terphenyl, C₃₆H₄₉I, (III), crystallize in space group Pnma. They are isomorphous and isostructural with a plane of symmetry through the centre of the mol­ecule. The C–halide bond distances are 1.745 (3), 1.910 (4) and 2.102 (6) Å for (I)–(III), respectively.     

6,6′‐Dimethoxygossypolone

6,6′‐Dimethoxygossypolone (systematic name: 7,7′‐dihydroxy‐5,5′‐diisopropyl‐6,6′‐dimethoxy‐3,3′‐dimethyl‐1,1′,4,4′‐tetraoxo‐2,2′‐binaphthalene‐8,8′‐dicarbaldehyde), C₃₂H₃₀O₁₀, is a dimeric molecule formed by oxidation of 6,6′‐dimethoxygossypol. When crystallized from acetone, 6,6′‐dimethoxygossypolone has monoclinic (P2₁/c) symmetry, and there are two molecules within the asymmetric unit. Of the four independent quinoid rings, three display flattened boat conformations and one displays a flattened chair/half‐chair conformation. The angles between the planes of the two bridged naphthoquinone structures are fairly acute, with values of about 68 and 69°. The structure has several intramolecular O—H...O and C—H...O hydrogen bonds and several weak intermolecular C—H...O hydrogen bonds, but no intermolecular O—H...O hydrogen bonds.     

Silica Hybrid Containing （ R ）-2, 2＇-Binaphtho-20-crown-6 Moieties via the Sol-Gel Process

(R)-6,6‘-Bis(triethoxysilylethen-2-yl)-2,2-‘binaphtho-20-crown-6(precursor,R-2) derived form(R)-2,2-BINOL derivative was synthesized by Pd-catelyzed Heck reaction of (R)-6-6‘-dibromo-2,2‘-binaphtoh-20-crown-6(R-1) intermediate with vinyltriethoxysilane. The hydrolysis and polycondensatlon ofthe precursor gave rise to the corresponding xerogei. Both pre cursor and xerogei were analysed by NMR, FT-IR, UV, CD spectra, fluorescent spectroscopy, polarimetry and elemental analysis. The precursor and xerogei can emit strong blue fluorescenee and are expected to have the potential appficatiou inthe separation of chiral molecules as fluorescent sensor. The precursor exhibits strong Cotton effect in its circular dichroism (CD) spectrum indicating that it is a highly rigid structure.     

Novel,Complex Flavonoids from Mallotus philippensis (Kamala Tree)

One new flavanone, 4′‐hydroxyisorottlerin ( 2 ), and two new chalcone derivatives, kamalachalcones C ( 3 ) and D ( 4 ), were isolated from Mallotus philippensis (kamala tree). The largest compound ( 4 ; M_r 1098 g/mol) was shown to possess a unique, fused‐ring system made of two hydroxy‐chalcone units, giving rise to eight fused benzene/pyran units. From the same plant, the following six known compounds were also isolated: kamalachalcone A ( 5 ) and B ( 6 ), isoallorottlerin ( 7 ), isorottlerin ( 8 ), 5,7‐dihydroxy‐8‐methyl‐6‐prenylflavanone ( 9 ); 6,6‐dimethylpyrano(2″,3″: 7,6)‐5‐hydroxy‐8‐methylflavanone ( 10 ), and rottlerin ( 1 ). The structures of the new compounds were confirmed by in‐depth spectral analyses, including 2D‐NMR techniques, and the full ¹³C‐NMR assignments of the known flavanones 1 and 7 – 10 are published for the first time.     

Synthesis of Phosphorylated Derivatives of Sucrose: 6,6′-di-Phosphonate, 6- and 6′-Phosphonates,and 6,6′-di-Phosphine

Reaction of 6,6′dideoxy-6,6′di-iodo-1′,2,3,3′,4,4′-hexa-O-benzylsucrose with triethyl phosphite afforded the corresponding 6,6′-diphosphonate. Selective phosphonylation either at the C-6 or 6-6′ position was also possible providing the corresponding sucrose mono-phosphonates. Reaction of 6,6′-dichloro-hexa-O-benzylsucrose with diphenylphoshine anion afforded the 6,6′-diphosphinosucrose.     

Highly Soluble and Green Indigo Dyes: 4,4′,7,7′‐Tetraalkoxy‐5,5′‐diaminoindigotins

Two new types of 4,4′,7,7′‐tetraalkoxyindigotins, 1a – f and 2a – f along with the new N‐substituted indigotins 4e – f , were synthesized from dinitrobenzaldehydes 5a – f , which were prepared from 2‐hydroxy‐5‐methoxybenzaldehyde ( 7 ) via dialkoxybenzaldehydes 6a – f (Scheme). The new dialkoxyindigotin 3g was obtained from dialkoxybenzaldehyde 6g via nitrobenzaldehyde 8g . The 1,4‐dialkoxy‐2,3‐dinitrobenzenes 9 were isolated as by‐products. The 4,4′,7,7′‐tetraalkoxy‐5,5′‐diaminoindigotins 1 are soluble in organic solvents, and their solutions are green, which is highly uncommon for indigotins and is primarily caused by electronic effects of substituents, steric effects playing a minor role. The indigotins 1 produce a strong red shift of the longest‐wavelength absorption and negative solvatochromism indicating the predominance of polar resonance structures in the ground state. Tautomeric structures were excluded. These indigotins are valuable compounds for technical applications, for synthetic purposes, and for analytical studies. SANS (Small‐angle neutron scattering) experiments showed that certain 4,4′,7,7′‐tetraalkoxy‐5,5′‐diaminoindigotins 1 form rod‐like aggregates in solution. The similarly substituted 4,4′,7,7′‐tetraalkoxy‐5,5′‐dinitroindigotins 2 are far less soluble. They produce red monoanions (preferably dimers) and bluish‐purple dianions in organic solvents.     

Synthesis of Novel Monodentate Phosphoramidites and Their Application in Iridium‐Catalyzed Asymmetric Hydrogenations

New monodentate H₈‐binaphthol based phosphoramidites 6 b–i have been prepared. Starting from (S)‐3,3′‐dibromo‐5,5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl‐2,2′‐diol 3 , a general protocol for the synthesis of ligands 6 is presented. A small ligand library bearing aryl substituents in the 3,3′‐position of the binaphthol core was synthesized and successfully tested in the iridium‐catalyzed asymmetric hydrogenation of 2‐amidocinnamates to obtain different α‐amino acid derivatives in up to 99 % ee.     

6‐Bromoindigo dye

6‐Bromoindigo (MBI) [systematic name: 6‐bromo‐2‐(3‐oxo‐2,3‐dihydro‐1H‐indol‐2‐ylidene)‐2,3‐dihydro‐1H‐indol‐3‐one], C₁₆H₉BrN₂O₂, crystallizes with one disordered molecule in the asymmetric unit about a pseudo‐inversion center, as shown by the Br‐atom disorder of 0.682 (3):0.318 (3). The 18 indigo ring atoms occupy two sites which are displaced by 0.34 Å from each other as a result of this packing disorder. This difference in occupancy factors results in each atom in the reported model used to represent the two disordered sites being 0.08 Å from the higher‐occupancy site and 0.26 Å from the lower‐occupancy site. Thus, as a result of the disorder, the C—Br bond lengths in the disordered components are 0.08 and 0.26 Å shorter than those found in 6,6′‐dibromoindigo (DBI) [Süsse & Krampe (1979). Naturwissenschaften, 66 , 110], although the distances within the indigo ring are similar to those found in DBI. The crystals are also twinned by merohedry. Stacking interactions and hydrogen bonds are similar to those found in the structures of indigo and DBI. In MBI, an interaction of the type C—Br...C replaces the C—Br...Br interactions found in DBI. The interactions in MBI were calculated quantum mechanically using density functional theory and the quantum theory of atoms in molecules.     

Diarylheptanoids from the Rhizomes of Alpinia officinarum

A novel dimeric diarylheptanoid, (5R,5′R)‐7,7′‐(6,6′‐dihydroxy‐5,5′‐dimethoxy[1,1′‐biphenyl]‐3,3′‐diyl)bis[5‐methoxy‐1‐phenylheptan‐3‐one] ( 1 ), and two new diarylheptanoids, (4E,6R)‐6‐hydroxy‐7‐(4‐hydroxy‐3‐methoxyphenyl)‐1‐phenylhept‐4‐en‐3‐one ( 2 ) and (4E,6R)‐6‐hydroxy‐1,7‐diphenylhept‐4‐en‐3‐one ( 3 ), together with seven known diarylheptanoids, were isolated from the rhizomes of Alpinia officinarum. Their structures were elucidated by application of extensive spectroscopic analyses and the modified Mosher method.     

Reduction of Capsorubin and Cryptocapsin

(6′S)‐ and (6′R)‐‘Capsorubol‐6‐one' (=(3S,3′S,5R,5′R,6′S)‐ and (3S,3′S,5R,5′R,6′R)‐3,3′,6′‐trihydroxy‐κ,κ‐caroten‐6‐one; 8 and 9 , resp.), (6S,6′R)‐ and (6R,6′R)‐capsorubol (=3S,3′S,5R,5′R,6S,6′R)‐ and (3S,3′S,5R,5′R,6R,6′R)‐κ,κ‐carotene‐3,3′,6,6′‐tetrol; 11 and 12 , resp.) and (6′S)‐ and (6′R)‐cryptocapsol (=(3′S,5′R,6′S)‐ and (3′S,5′R,6′R)‐β,κ‐carotene‐3′,6′‐diol; 5 and 6 , resp.) were prepared in crystalline from by the reduction of capsorubin (=(3S,3′S,5R,5′R)‐3,3′‐dihydroxy‐κ,κ‐carotene‐6,6′‐dione; 7 ) and cryptocapsin (=(3′S,5′R)‐3′‐hydroxy‐β,κ‐caroten‐6′‐one; 4 ) and characterized by their UV/VIS, CD, ¹H‐NMR, and mass spectra.     

Vapochromic Ionic Liquids from Metal–Chelate Complexes Exhibiting Reversible Changes in Color,Thermal, and Magnetic Properties

Vapor‐ and gas‐responsive ionic liquids (ILs) comprised of cationic metal‐chelate complexes and bis(trifluoromethanesulfonyl)imide (Tf₂N) have been prepared, namely, [Cu(acac)(BuMe₃en)][Tf₂N] ( 1 a ), [Cu(Bu‐acac)(BuMe₃en)][Tf₂N] ( 1 b ), [Cu(C₁₂‐acac)(Me₄en)][Tf₂N] ( 1 c ), [Cu(acac)(Me₄en)][Tf₂N] ( 1 d ), and [Ni(acac)(BuMe₃en)][Tf₂N] ( 2 a ) (acac=acetylacetonate, Bu‐acac=3‐butyl‐2,4‐pentanedionate, C₁₂‐acac=3‐dodecyl‐2,4‐pentanedionate, BuMe₃en=N‐butyl‐N,N′,N′‐tetramethylethylenediamine, and Me₄en=N,N,N′,N′‐trimethylethylenediamine). These ILs exhibited reversible changes in color, thermal properties, and magnetic properties in response to organic vapors and gases. The Cu^II‐containing ILs are purple and turn blue‐purple to green when exposed to organic vapors, such as acetonitrile, methanol, and DMSO, or ammonia gas. The color change is based on the coordination of the vapor molecules to the cation, and the resultant colors depend on the coordination strength (donor number, DN) of the vapor molecules. The vapor absorption caused changes in the melting points and viscosities, leading to alteration in the phase behaviors. The IL with a long alkyl chain ( 1 d ) transitioned from a purple solid to a brown liquid at its melting point. The Ni^II‐containing IL ( 2 a ) is a dark red diamagnetic liquid, which turned into a green paramagnetic liquid by absorbing vapors with high DN. Based on the equilibrium shift from four‐ to six‐coordinated species, the liquid exhibited thermochromism and temperature‐dependent magnetic susceptibility after absorbing methanol.     

Synthesis and properties of poly(amic acid)s and polyimides based on 2,2′,6,6′‐biphenyltetracarboxylic dianhydride

Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2′,6,6′‐biphenyltetracarboxylic dianhydride (2,2′,6,6′‐BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2′,6,6′‐BPDA and 4,4′‐(1,3‐phenylenedioxy)dianiline was converted to the polyimide by thermal treatment. The heating at 300 °C under nitrogen did not complete thermal imidization of PAAs having glass‐transition temperatures (T_g)s higher than 300 °C to the corresponding PIs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6385–6393, 2006     

Synthesis of Some Novel Amino Phenols with Octahydro‐1,1′‐binaphthyl Backbone

A series of new octahydro‐1,1′‐binaphthyl derivatives, namely (R)‐(+)‐2‐(N, N‐dialkylamino)‐2′‐hydroxy‐5,5′,6,6′,7, 7′,8,8′‐octahydro‐1,1′‐binaphthyls (7,9), have been synthesized. Their asymmetric induction for enantioselective addition of Et₂Zn to benzaldehyde was examined and it was found that (R)‐(+)‐2‐(N‐cyclohexyl‐N‐methylamino)‐2′‐hydroxy‐5, 5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthyl (9c) exhibited the best asymmetric induction among the ligands prepared, up to 55% ee of 1‐phenylpropanol being obtained.     

Intrinsically microporous polyimides containing spirobisindane and phenazine units: Synthesis,characterization and gas permeation properties

A new diamine containing spirobisindane and phenazine units, namely, 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine]‐7,7′‐diamine (TTSBIDA) was synthesized starting from commercially available 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane (TTSBI). TTSBI was oxidized to 3,3,3′,3′‐tetramethyl‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[indene]‐5,5′,6,6′‐tetraone (TTSBIQ) which was subsequently condensed with 4‐nitro‐1,2‐phenylenediamine to obtain 3,3,3′,3′‐tetramethyl‐7,7′‐dinitro‐2,2′,3,3′‐tetrahydro‐1,1′‐spirobi[cyclopenta[b]phenazine] (TTSBIDN). TTSBIDN was converted into TTSBIDA by reduction of the nitro groups using hydrazine hydrate in the presence of Pd/C as the catalyst. A series of new polyimides of intrinsic microporosity (PIM‐PIs) were synthesized by polycondensation of TTSBIDA with commercially available aromatic dianhydrides. PIM‐PIs exhibited amorphous nature, high thermal stability (T₁₀ > 480 °C) and intrinsic microporosity (BET surface area = 59–289 m²/g). The gas permeation characteristics of films of selected PIM‐PIs were evaluated and they exhibited appreciable gas permeability as well as high selectivity. The CO₂ and O₂ permeability of PIM‐PIs were in the range 185.4–39.2 and 30.6–6.2 Barrer, respectively. Notably, polyimide derived from TTSBIDA and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (PIM‐PI‐6FDA) exhibited high CO₂ and O₂ permeability of 185.4 and 30.6 Barrer with CO₂/CH₄ and O₂/N₂ selectivity of 43.1 and 5.1, respectively. The data of PIM‐PI‐6FDA for CO₂/CH₄ and O₂/N₂ gas pairs were located near Robeson upper bound. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 766–775     

Preparation of 6,6′—Bisperfluoroalkylated BINOLs and Their Application in Asymmetric Alkylation of Benzaldehyde

6，6′-Bis(1H,1H,2H,2H-perfluorooctyl)-BINOL and 6,6′-bis(1H,1H,2H,2H-perfluorodecyl)-BINOL were synthesized through Suzuki coupling reaction and used in fluorous biphase asymmetric alkylation of benzldehyde,Good enantioselectivity was obtained and the catalysts could be recovered by liquid-liq-uid extraction.     

Synthesis and Asymmetric Enantioselective Addition of Chiral Polybinaphthyl and Polybinaphthol I.igands

Four chiral polymers P-1, P-2, P-3 and P-4 were synthesized by the polymerization of （S）-2,2＇-dioctoxy-1,1＇- binaphthyl-6,6＇-boronic acid （S-M-3） with （S）-6,6＇-dibromo-1,1＇-binaphthol （S-M-1）, （R）-6,6＇-dibromo-1,1＇- binaphthol （R-M-1）, （S）-3,3＇-diiodo-1,1＇-binaphthol （S-M-2） and （R）-3,3＇-diiodo-1,1＇-binaphthol （R-M-2） under Pd-catalyzed Suzuki reaction, respectively. All four polymers can show good solubility in some common solvents due to the nonplanarity of the polymers in the main chain backbone and flexible alkyl groups in the side chain. The analysis results indicate that specific rotation and circular dichroism （CD） spectral signals of the alternative S-S chiral polymers P-1 and P-3 are larger than those of S-R chiral polymers P-2 and P-4, but their UV-Vis and fluorescence spectra are almost similar. The results of asymmetric enantioselectivity of four polymers for diethylzinc addition to benzaldehyde indicate that catalytically active center is （R） or （S）-1, 1＇-binaphthol moieties.