Crystallization‐Induced Reversal from Dark to Bright Excited States for Construction of Solid‐Emission‐Tunable Squaraines

Squaraines (SQs) with tunable emission in the solid state is of great importance for various demands; however a remaining challenge is emission quenching upon aggregation. Herein, a unique SQ, named as CIEE‐SQ, is designed to exhibit strong emission in crystal, undergoing crystallization‐induced reverse from dark ¹(n+σ,π*) to bright ¹(π,π*) excited states. Such an excited state of CIEE‐SQ can be subtly tuned by molecular conformation changes during the unexpected temperature‐triggered single‐crystal to single‐crystal (SCSC) reversible transformation. Furthermore, co‐crystallization between CIEE‐SQ and chloroform largely stabilize the ¹(π,π*) state, enhancing the transition dipole moment and decreasing the reorganization energy to boost the fluorescence, which is promising in data encryption and decryption.     

Phenanthro[4,5‐fgh]quinoxaline‐Fused Subphthalocyanines: Synthesis,Structure, and Spectroscopic Characterization

A series of four phenanthro[4,5‐fgh]quinoxaline‐fused subphthalocyanine derivatives 0 – 3 containing zero, one, two, and three phenanthro[4,5‐fgh]quinoxaline moieties, respectively, were isolated from the mixed cyclotrimerization reaction of 2,9‐di‐tert‐butylphenanthro[4,5‐fgh]quinoxaline‐5,6‐dicarbonitrile with 4,5‐bis(2,6‐diisopropylphenoxy)phthalonitrile and characterized by a series of spectroscopic methods including MALDI‐TOF mass, ¹H NMR, electronic absorption, magnetic circular dichroism (MCD), and fluorescence spectroscopy. The molecular structures for the compounds 0 and 2 were clearly revealed on the basis of single‐crystal X‐ray diffraction analysis. Their electrochemical properties were also studied by cyclic voltammetry. In particular, theoretical calculations in combination with the electronic absorption and electrochemical analyses revealed the significant influence of the fused‐phenanthro[4,5‐fgh]quinoxaline units on the electronic structures.     

Can Non‐Kramers TmIII Mononuclear Molecules be Single‐Molecule Magnets (SMMs)?

In recent years, plentiful lanthanide‐based (Tb^III, Dy^III, and Er^III) single‐molecule magnets (SMMs) were studied, while examples of other lanthanides, for example, Tm^III are still unknown. Herein, for the first time, we show that by rationally manipulating the coordination sphere, two thulium compounds, 1 [(Tp)Tm(COT)] and 2 [(Tp*)Tm(COT)] (Tp=hydrotris(1‐pyrazolyl)borate; COT=cyclooctatetraenide; Tp*=hydrotris(3,5‐dimethyl‐1‐pyrazolyl)borate), can adopt the structure of non‐Kramers SMMs and exhibit their behaviors. Dynamic magnetic studies indicated that both compounds showed slow magnetic relaxation under dc field and a relatively high effective energy barrier (111 K for 1 , 46 K for 2 ). Magnetic diluted 1 a [(Tp)Tm_0.05Y_0.95(COT)] and 2 a [(Tp*)Tm_0.05Y_0.95(COT)] even exhibited magnetic relaxation under zero dc field. Relativistic ab initio calculations combined with single‐crystal angular‐resolved magnetometry measurements revealed the strong easy axis anisotropy and nearly degenerated ground doublet states. The comparison of 1 and 2 highlights the importance of local symmetry for obtaining Tm SMMs.     

Sequential Transformation of Zirconium(IV)‐MOFs into Heterobimetallic MOFs Bearing Magnetic Anisotropic Cobalt(II) Centers

Heterometallic metal–organic frameworks (MOFs) allow the precise placement of various metals at atomic precision within a porous framework. This new level of control by MOFs promises fascinating advances in basic science and application. However, the rational design and synthesis of heterometallic MOFs remains a challenge due to the complexity of the heterometallic systems. Herein, we show that bimetallic MOFs with MX₂(INA)₄ moieties (INA=isonicotinate; M=Co²⁺ or Fe²⁺; X=OH^?, Cl^?, Br^?, I^?, NCS^?, or NCSe^?) can be generated by the sequential modification of a Zr‐based MOF. This multi‐step modification not only replaced the linear organic linker with a square planar MX₂(INA)₄ unit, but also altered the symmetry, unit cell, and topology of the parent structure. Single‐crystal to single‐crystal transformation is realized so that snapshots for transition process were captured by successive single‐crystal X‐ray diffraction. Furthermore, the installation of Co(NCS)₂(INA)₄ endows field‐induced slow magnetic relaxation property to the diamagnetic Zr‐MOF.     

Selective Separation of Aliphatic Nitriles by Employing a Two‐Dimensional Interdigitated Coordination Polymer

A room‐temperature slow diffusion reaction of the metal nitrates [M=Zn^II and Co^II] with 5‐azido isophthalic acid (AIPA) and 1,4‐bis(4‐pyridyl)‐2,3‐diaza‐1,3‐butadiene (BPDB) resulted in a new two‐dimensional interdigitated coordination polymer, [M(C₈H₃N₃O₄)(C₁₂H₁₀N₄)] ⋅ DMF [DMF=dimethyl formamide (C₃H₇NO)]. The non‐bonded DMF molecules were found to exchange through a single‐crystal to single‐crystal (SCSC) fashion with many aliphatic nitrile compounds. More importantly, the present compound, I⋅DMF (Zn) appears to absorb cis ‐crotononitrile selectively from the cis /trans mixture as well as a mixture containing the structural isomer (allylnitrile). It also preferentially absorbs propionitrile from an equimolar mixture of acetonitrile, propionitrile, and butyronitrile (1:2:1). The cobalt compound exhibits anti‐ferromagnetic behavior.     

A Stable Crown Ether Complex with a Noble‐Gas Compound

Crown ethers have been known for over 50 years, but no example of a complex between a noble‐gas compound and a crown ether or another polydentate ligand had previously been reported. Xenon trioxide is shown to react with 15‐crown‐5 to form the kinetically stable (CH₂CH₂O)₅XeO₃ adduct, which, in marked contrast with solid XeO₃, does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO₃. The gas‐phase Wiberg bond valences and indices and the empirical bond valences indicate that the Xe‐ ‐ ‐O_crown bonds are predominantly electrostatic and are consistent with σ‐hole bonding. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO₃ and 15‐crown‐5 in (CH₂CH₂O)₅XeO₃ and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO₃ and (CH₂CH₂O)₅ reveal regions of negative EP on the oxygen atoms of (CH₂CH₂O)₅ and regions of high positive EP on the xenon atom, which are also in accordance with σ‐hole interactions.     

Indolizino[5,6‐b]quinoxaline Derivatives: Intramolecular Charge Transfer Characters and NIR Fluorescence

Indolizino[5,6‐b]quinoxaline derivatives ( 1 a and 1 b ) with a push–pull structure were prepared to show intramolecular charge‐transfer properties. Compounds 1 a and 1 b are strongly fluorescent in aprotic solvents while symmetrical derivatives ( 2 a and 2 b ) were non‐fluorescent. The π‐expanded α–α linked dimer ( 10 ) of indolizino[5,6‐b]quinoxaline 1 b was serendipitously obtained to show NIR absorption over 800 nm and the fluorescence edge reached to 1400 nm.     

Coupling Magnetic Single‐Crystal Co2Mo3O8 with Ultrathin Nitrogen‐Rich Carbon Layer for Oxygen Evolution Reaction

Transition‐metal oxides as electrocatalysts for the oxygen evolution reaction (OER) provide a promising route to face the energy and environmental crisis issues. Although palmeirite oxide A₂Mo₃O₈ as OER catalyst has been explored, the correlation between its active sites (tetrahedral or octahedral) and OER performance has been elusive. Now, magnetic Co₂Mo₃O₈@NC‐800 composed of highly crystallized Co₂Mo₃O₈ nanosheets and ultrathin N‐rich carbon layer is shown to be an efficient OER catalyst. The catalyst exhibits favorable performance with an overpotential of 331 mV@10 mA cm^?2 and 422 mV@40 mA cm^?2, and a full water‐splitting electrolyzer with it as anode catalyst shows a cell voltage of 1.67 V@10 mA cm^?2 in alkaline. Combined HAADFSTEM, magnetic, and computational results show that factors influencing the OER performance can be attributed to the tetrahedral Co sites (high spin, t₂³e⁴), which improve the OER kinetics of rate‐determining step to form *OOH.     

K2Au(IO3)5 and β‐KAu(IO3)4: Polar Materials with Strong SHG Responses Originating from Synergistic Effect of AuO4 and IO3 Units

Two new polar potassium gold iodates, namely, K₂Au(IO₃)₅ (Cmc2₁) and β‐KAu(IO₃)₄ (C2), have been synthesized and structurally characterized. Both compounds feature zero‐dimensional polar [Au(IO₃)₄]^? units composed of an AuO₄ square‐planar unit coordinated by four IO₃^? ions in a monodentate fashion. In β‐KAu(IO₃)₄, isolated [Au(IO₃)₄]^? ions are separated by K⁺ ions, whereas in K₂Au(IO₃)₅, isolated [Au(IO₃)₄]^? ions and non‐coordinated IO₃^? units are separated by K⁺ ions. Both compounds are thermally stable up to 400 °C and exhibit high transmittance in the NIR region (λ=800–2500 nm) with measured optical band gaps of 2.65 eV for K₂Au(IO₃)₅ and 2.75 eV for β‐KAu(IO₃)₄. Powder second‐harmonic generation measurements by using λ=2.05 μm laser radiation indicate that K₂Au(IO₃)₅ and β‐KAu(IO₃)₄ are both phase‐matchable materials with strong SHG responses of approximately 1.0 and 1.3 times that of KTiOPO₄, respectively. Theoretical calculations based on DFT methods confirm that such strong SHG responses originate from a synergistic effect of the AuO₄ and IO₃ units.     

A Novel and Efficient Synthesis of 3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐ones (=3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐1‐benzopyran‐2‐ones)

An efficient one‐pot synthesis of 3‐[(4,5‐dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐one (=3‐[(4,5‐dihydro‐1H‐pyrrol‐3yl)carbonyl]‐2H‐1‐benzopyran‐2‐one) derivatives 4 by a four‐component reaction of a salicylaldehyde 1 , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one, a benzylamine 2 , and a diaroylacetylene (=1,4‐diarylbut‐2‐yne‐1,4‐dione) 3 in EtOH is reported. This new protocol has the advantages of high yields (Table), and convenient operation. The structures of these coumarin (=2H‐1‐benzopyran‐2‐one) derivatives, which are important compounds in organic chemistry, were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

Synthese und Reaktivität von 2‐Brom‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol Molekülstruktur von Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl)

Synthesis and Reactivity of 2‐Bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborole Molecular Structure of Bis(1,3‐diethyl‐2,3‐dihydro‐1 H ‐1,3,2‐benzodiazaborol‐2‐yl The reaction of a slurry of calcium hydride in toluene with N,N′‐diethyl‐o‐phenylenediamine ( 1 ) and boron tribromide affords 2‐bromo‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol ( 2 ) as a colorless oil. Compound 2 is converted into 2‐cyano‐1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 3 ) by treatment with silver cyanide in acetonitrile. Reaction of 2 with an equimolar amount of methyllithium affords 1,3‐diethyl‐2‐methyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborole ( 4 ). 1,3,2‐Benzodiazaborole is smoothly reduced by a potassium‐sodium alloy to yield bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐yl] ( 7 ), which crystallizes from n‐pentane as colorless needles. Compound 7 is also obtained from the reaction of 2 and LiSnMe₃ instead of the expected 2‐trimethylstannyl‐1,3,2‐benzodiazaborole. N,N′‐Bis(1,3‐diethyl‐2,3‐dihydro‐1 H‐1,3,2‐benzodiazaborol‐2‐ yl)‐1,2‐diamino‐ethane ( 6 ) results from the reaction of 2 with Li(en)C≡CH as the only boron containing product. Compounds 2 – 4 , 6 and 7 are characterized by means of elemental analyses and spectroscopy (IR, ¹H‐, ¹¹B{¹H}‐, ¹³C{¹H}‐NMR, MS). The molecular structure of 7 was elucidated by X‐ray diffraction analysis.     

An efficient synthesis of 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles

Some new target products 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j have been synthesized by reaction of 2‐bromo‐1‐phenylethanone and compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j which were prepared from the combination of thiosemicarbazide and (E)‐3‐aryl‐1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐prop‐2‐en‐1‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j . All the structures were established by MS, IR, CHN, and ¹H NMR spectra data. Synthesis of structure diversity is applied. J. Heterocyclic Chem., (2011).     

Preparation of 2‐amino‐5‐methyl‐7H‐1,3,4‐thiadiazolo[3,2‐α]pyrimidin‐7‐ones

2‐Amino substituted 7H‐1,3,4‐thiadiazolo[3,2‐α]pyrimidin‐7‐ones 11a‐e were prepared by the reaction of 2‐bromo‐5‐amino‐1,3,4‐thiadiazole ( 1b ) and diketene ( 8 ), subsequent cyclocondensation ( 9b → 3b ) and displacement of the bromo substituents by the reaction with primary or secondary amines ( 3b → 11a‐e ). The hydrogen atom 6‐H in the heterobicycle 3b is replaced by a Cl or Br atom in the transformation of 3b → 14a,b. The 2‐bromo‐6‐chloro compound 14a reacts chemoselectively in the 2‐position with dimethylamine ( 14a → 15 ). The structure elucidations are based on one‐ and two‐dimensional NMR techniques including a heteronuclear NOE measurement.     

Enantioselective Synthesis of Ethyl 4,5,7,8,9‐Penta‐O‐acetyl‐2,6‐anhydro‐ 3‐deoxy‐D‐erythro‐L‐gluca‐nononate: a 2‐Monodeoxygenated Derivative of `2‐Keto‐3‐deoxy‐D‐glycero‐D‐galacto‐nononic Acid'

A study aimed at developing an enantioselective synthesis of the title compound 23 , a 2‐monodeoxy analogue of the naturally occurring (+)‐2‐keto‐3‐deoxy‐D ‐glycero‐D ‐galacto‐2‐nononic acid (KDN), is reported. From D ‐mannose as starting material, the chiral 1,3‐diene 10 , activated by a silyloxy substituent at C(2), was prepared in six steps (Scheme 1). However, the intermediates were often contaminated with varying amounts of by‐products arising from overoxidation during cleavage with periodic acid. An alternative route starting from the inexpensive and readily available D ‐isoascorbic acid ( 12 ), though a little longer than the first, satisfactorily circumvented the purification problem and led to the desired dienes 17 in good yields (scheme 2). The [Co^II(S,S)‐(+)‐salen]‐catalyzed hetero‐Diels‐Alder reactions of the aforementioned dienes with ethyl glyoxylate proceeded smoothly at room temperature, giving the dihydropyrano adducts 18 in moderate yields (Scheme 3). Dihydroxylation of 18a followed by reduction of the keto function gave the desired 4,5‐trans dihydroxy moiety of the KDN framework (Scheme 4, see 21 ). The spectroscopic data of the penta‐O‐acetylated 2‐deoxy‐KDN ethyl ester 23 were consistent with those reported for the corresponding methyl ester derived from natural KDN.     

具有U构型的二{1-甲硫基-1-[1-苯基-1-(1-苯基-3-甲基-5-氧代-4,5二氢吡唑-4-烯)-甲氨基]亚氨甲基}二硫醚的晶体结构

The reaction of 1-phenyl-3-methyl-4-benzoyl-2,5-dihydro-1H-pyrazol-5-one (PMBP) and methyldithiocarbazate (mdtc) in methanol results in formation of a yellow crystalline solid, adduct of 1-phenyl-3-methyl-4benzoyl-2,5-dihydro-lH-pyrazol-5-one and methyldithiocarbazate. When the yellow solids were dissolved in a mixture of methanol and ether (1:4), a red crystal, which is an oxidation product of the former, was obtained by allowing solvent to evaporate for a few days at room temperature. The X-ray analysis of the red crystal indicates that it is a novel disulfide with a special structure like a “U” conformation in the solid state.     

Synthesis of some new 1‐acyl‐5‐aryl‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐4,5‐dihydro‐1H‐pyrazole

Some new compounds (E)‐3‐aryl‐1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐prop‐2‐en‐1‐ones 5a–e were prepared by 1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐ethanone and various aromatic aldehydes. Then one pot reaction was happened by compounds 5a–e with hydrazine hydrate in acetic acid or propionic acid, respectively, to give the title compounds 1acyl‐5‐aryl‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐4,5‐dihydro‐1H‐pyrazoles 6a–i . All structures were established by MS, IR, CHN, ¹H‐NMR and ¹³C‐NMR spectral data. J. Heterocyclic Chem., (2012).     

Preparation of 2‐phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline and 2‐methyl‐4‐oxo‐3,4‐dihydroquinazoline derivatives formation

The cyclization of phenacyl anthranilate has been studied with the aim to develop the synthesis of 2‐(2′‐aminophenyl)‐4‐phenyloxazole. However, a different course of the reaction than expected was observed. 2‐Phenyl‐2‐hydroxymethyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 3a ) was formed by the reaction of phenacyl anthranilate ( 2 ) with ammonium acetate under various conditions. 3‐Hydroxy‐2‐phenyl‐4(1H)‐quinolinone ( 4 ) arose by heating compound 3a in acetic acid. The same compound was obtained by melting compound 3a , but the yield was lower. Different types of products resulted in the reaction of compound 3a with acetic anhydride. Under mild conditions acetylated products 2‐acetoxymethyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 7a ) and 2‐acetoxymethyl‐3‐acetyl‐2‐phenyl‐4‐oxo‐1,2,3,4‐tetrahydroquinazoline ( 8 ) were prepared. If the reaction was carried out under reflux of the reaction mixture, molecular rearrangement took place to give cis and trans 2‐methyl‐4‐oxo‐3‐(1‐phenyl‐2‐acetoxy)vinyl‐3,4‐dihydroquinazolines ( 9a and 9b ). All prepared compounds have been characterised by their ¹H, ¹³C and ¹⁵N NMR spectra, IR spectra and MS.     

Gas‐phase tautomerism in hydroxy azo dyes – from 4‐phenylazo‐1‐phenol to 4‐phenylazo‐anthracen‐1‐ol

The tautomeric constants of a series of azo dyes were estimated in the gas phase by using electron ionization mass spectrometry. It was shown that the relative amount of the keto tautomer increases from 4‐phenylazo‐1‐phenol to 4‐phenylazo‐anthracen‐1‐ol, thus confirming the quantum‐chemical predictions. The existence of the enol tautomer of 4‐phenylazo‐anthracen‐1‐ol is shown for the first time by mass spectrometry in the gas phase. This finding is supported by flash photolysis measurements in solution. Copyright © 2010 John Wiley & Sons, Ltd.     

4‐Hydroxy‐7‐methoxy‐2‐methyl‐5H‐1‐benzopyrano[4,3‐b]pyridin‐5‐one

The title compound, C₁₄H₁₁NO₄, consists of a methoxy‐substituted coumarin skeleton fused to a 2‐methyl‐4‐pyridone ring. The ring system of the mol­ecule is approximately planar and the methoxy group is roughly coplanar with the ring plane. The 4‐pyridone ring exists in a 4‐hydroxy tautomeric form and is stabilized by an intramolecular hydrogen bond between the O—H and C=O groups. Comparison of the results with those found for other structures containing the 4‐pyridone substructure reveals a substantial effect of the nature of the substituents bonded to the pyridine ring on the keto–enol tautomerism.