Spiro Junction Research Articles

Constructing thermally activated delayed fluorescence dendrimers for solution processable blue OLEDs by molecular engineering of peripheral dendrons

Thermally activated delayed fluorescence (TADF) dendrimers with definite chemical structure are ideal candidate to fabricate high-efficiency organic light emitting diodes (OLEDs) using lower-cost solution processing techniques. Nevertheless, there still remains a challenge to construct molecular architectures of dendrimer-based TADF emitters that show easily controlled photophysical properties and superior carrier transporting capability simultaneously. Herein, we integrate peripheral dendrons possessing bipolar transmission capability with donor-acceptor skeleton through spiro junction to construct newly designed dendritic TADF emitters, TrzSpiroAc-tmCP and TrzSpiroAc-tmCPCN. By precisely regulating peripheral dendrons in these newly designed molecules, the lifetime and proportion of delayed components for TrzSpiroAc-tmCPCN are meticulously modulated to be 3.1 μs and 26.0 %, respectively, and thus exhibiting enhanced reverse intersystem crossing process with rate constant of 3.2 × 105 s−1 and excellent photoluminescence quantum yield over 70 %. Solution processable OLEDs based on TrzSpiroAc-tmCPCN with blue emission are achieved, and the external quantum efficiency value can exceed 10 %. Overall, this work manifests a valid strategy to tackle the imperative need for further exploring high-efficiency TADF dendrimers by integrating molecular engineering of peripheral dendritic units with constructing spiro junction between emission core and dendritic units.

Exploration of the Solid-State Sorption Properties of Shape-Persistent Macrocyclic Nanocarbons as Bulk Materials and Small Aggregates.

Porous molecular materials combine benefits such as convenient processability and the possibility for atom-precise structural fine-tuning which makes them remarkable candidates for specialty applications in the areas of gas separation, catalysis, and sensing. In order to realize the full potential of these materials and guide future molecular design, knowledge of the transition from molecular properties into materials behavior is essential. In this work, the class of compounds termed cycloparaphenylenes (CPPs)-shape-persistent macrocycles with built-in cavities and radially oriented π-systems-was selected as a conceptually simple class of intrinsically porous nanocarbons to serve as a platform for studying the transition from analyte sorption properties of small aggregates to those of bulk materials. In our detailed investigation, two series of CPPs were probed: previously reported hoop-shaped [n]CPPs and a novel family of all-phenylene figure-8 shaped (lemniscal) bismacrocycles, termed spiro[n,n]CPPs. A series of nanocarbons with different macrocycle sizes and heteroatom content have been prepared by atom-precise organic synthetic methods, and their structural, photophysical, and electronic attributes were disclosed. Detailed experimental studies (X-ray crystallography, gas sorption, and quartz-crystal microbalance measurements) and quantum chemical calculations provided ample evidence for the importance of the solid-state arrangement on the porosity and analyte uptake ability of intrinsically porous molecular nanocarbons. We demonstrate that this molecular design principle, i.e., incorporation of sterically demanding spiro junctions into the backbone of nanohoops, enables the manipulation of solid-state morphology without significantly changing the nature and size of the macrocyclic cavities. As a result, the novel spiro[n,n]CPPs showed a remarkable performance as high affinity material for vapor analyte sensing.

Crystal structures of three cyclohexane-based \u03b3-spirolactams: determination of configurations and conformations

The title compounds, 2-azaspiro[4.5]deca-1-one, C9H15NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C10H17NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C10H17NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N–H···O hydrogen bonds.

5′-Benzylidene-1′′-methyl-4′′-phenyltrispiro[1,3-dioxolane-2,1′-cyclohexane-3′,3′′-pyrrolidine-2′′,3′′′-indole]-4′,2′′′-dione

In the title compound, C32H30N2O4, two spiro links connect the methyl-substituted pyrrolidine ring to the oxindole and cyclohexanone rings. The cyclohexanone ring is further connected to the dioxalane ring by a third spiro junction. Both the pyrrolidine and dioxalane rings adopt a twist conformation. The indole ring is nearly planar, with a maximum deviation of 0.0296 (7) Å, and the cyclohexanone ring adopts a distorted boat conformation. In the crystal, C—H...O and N—H...N hydrogen-bonding interactions connect molecules into chains running parallel to thebaxis, which are further linked into layers parallel to theabplane by C—H...O hydrogen bonds.

How Dimerization Through a Spiro Junction Modifies the Nonlinear Optical Properties of a Push–Pull Organic Dye: Insights from Theory and Hyper‐Rayleigh Scattering

AbstractThe second‐order nonlinear optical (NLO) properties of a push–pull monomer, as well as of its dimer composed of two monomeric units connected through a non‐conjugated spiro junction, are investigated by means of hyper‐Rayleigh scattering (HRS) and quantum chemical calculations. It is shown that dimerization to form a molecule with an orthogonal geometry enhances the first hyperpolarizability by circa 20 % and induces a decrease of the dipolar character of the HRS response. Theoretical calculations correlate well with experimental measurements and allow an in‐depth rationalization of the impact of the spiro linkage on the NLO properties through a detailed analysis of the relevant electronic excited states.

Crystal structure of 5''-benzyl-idene-1'-methyl-4'-phenyl-tri-spiro-[ace-naphthyl-ene-1,2'-pyrrolidine-3',1''-cyclo-hexane-3'',2'''-[1,3]dioxane]-2,6''-dione.

In the title compound, C36H31NO4, two spiro links connect the methyl-substituted pyrrolidine ring to the ace-naphthyl-ene and cyclo-hexa-none rings. The cyclo-hexa-none ring is further connected to the dioxalane ring by a third spiro junction. The five-membered ring of the ace-naphthylen-1-one ring system adopts a flattened envelope conformation with the ketonic C atom as flap, whereas the dioxalane and pyrrolidine rings each have a twist conformation. The cyclo-hexa-none ring assumes a boat conformation. Three intra-molecular C-H⋯O hydrogen bonds involving both ketonic O atoms as acceptors are present. In the crystal, C-H⋯O hydrogen bonds connect centrosymmetrically related mol-ecule into chains parallel to the b axis, forming rings of R 2 (2)(10)and R 2 (2)(8) graph-set motifs.

Crystal structure of 5''-(4-chloro-benzyl-idene)-4'-(4-chloro-phen-yl)-1'-methyltri-spiro[acenapthylene-1,2'-pyrrolidine-3',1''-cyclo-hexane-3'',2'''-[1,3]dioxane]-2(1H),6''-dione.

In the title compound, C36H29Cl2NO4, two spiro links connect the methyl-substituted pyrrolidine ring to the ace­naphthyl­ene and cyclo­hexa­none rings. The cyclo­hexa­none ring is further connected to the dioxalane ring by a third spiro junction. The five-membered ring of the ace­naphthylen-1-one ring system adopts a flattened envelope conformation, with the ketonic C atom as the flap, whereas the dioxalane and pyrrolidine rings each have a twist conformation. The cyclo­hexenone ring assumes a boat conformation. An intra­molecular C—H⋯O hydrogen-bond inter­action is present. In the crystal, mol­ecules are linked by non-classical C—H⋯O hydrogen bonds, forming chains extending parallel to the a axis.

Construction of Structurally Inspiring Spiroisoxazolines.

Spiroisoxazolines of natural and synthetic origin are of recurring interest to researchers engaged in the areas of natural product synthesis and methodology. The spiroisoxazoline motif is a ubiquitous feature for a number of marine natural products of the order Verongida and display an array of interesting properties ranging from central nervous system (CNS) to antitumor and antifungal effects. Many of these natural products include a framework derived from isoxazoline and are characterized by unique spiro junction at C-5 position to an isoxazoline. Inspired from these secondary active metabolites, additional analogs resembling spiroisoxazoline structural pattern were designed and developed for the exploration of possible bioactivity. The current review provides an overview of various methodologies applied in the construction of spiroisoxazolines of pharmacological and biomedical interest. Keywords: Spiroisoxazolines, heterocycles, 1, 3-Dipolar cycloadditions, condensations, intramolecular cyclizations, regioselectivity.

Methyl 4-anilino-2′,5-dioxo-1′,2′-dihydro-5H-spiro[furan-2,3′-indole]-3-carboxylate

In the title compound, C19H14N2O5, the spiro junction links an oxindole moeity and a furan ring, which subtend a dihedral angle of 83.49 (6)°. The mol­ecular structure features an N—H⋯O hydrogen bond, which generates an S(6) ring motif. The crystal packing is governed by two N—H⋯O inter­actions, one of which generates a centrosymmetric R 2 2(14) dimer. The other N—H⋯O inter­action along with a C—H⋯O hydrogen bond contributes to the formation of a C 2 2[R 2 2(9)] dimeric chain running along the b-axis direction.

Methyl 2,2-dimethoxy-8-oxo-1-oxaspiro[4.5]deca-6,9-diene-3-carboxylate

In the title mol­ecule, C13H16O6, the cyclo­hexa-1,4-diene ring adopts a flat boat conformation (r.m.s. deviation from planarity = 0.060 Å) and the five-membered tetra­hydro­furan ring adopts an envelope conformation with the carboxyl group-substituted C atom as the flap. The dihedral angle at the spiro junction is 89.1 (1)°. In the crystal, mol­ecules are linked through weak C—H⋯O and van der Waals inter­actions.

1′-(2-Chlorophenyl)-5,6,5′,6′,7′,7a′-hexahydro-1′H,1′′H-dispiro[imidazo[2,1-b][1,3]thiazole-2,2′-pyrrolizine-3′(2′H),3′′-indole]-2′′,3(2H,3′′H)-dione

In the title compound, C24H21ClN4O2S, the two adjacent spiro junctions link an almost planar (r.m.s. deviation = 0.017 Å) 2-oxindole ring, a hexa­hydro-1H-pyrrolizine ring and a tetra­hydro­imidazo[2,1-b]thia­zole ring. In the crystal, inversion dimers linked by pairs of N—H⋯N hydrogen bonds occur, generating an R 2 2(16) loop.

Crystal structure of 3′′′-(2,6-dichlorophenyl)-1′-methyl-4′,4′′′-bis(4- chlorophenyl)-4′′′,5′′′-dihydroindole-3-spiro-2′-pyrrolidine-3′-spiro-1′- cyclopentane-3″-spiro-5′′′-[1,2]oxazole-2(3H),2″-dione hemihydrate, C36H27Cl4N3O3 · 0.5H2O

C36H28Cl4N3O3.50, orthorhombic, Iba2 (no. 45), a = 20.844(4) A, b = 27.280(6) A, c = 12.031(2) A, V = 6841.1 A, Z = 8, Rgt(F) = 0.073, wRref(F) = 0.212, T = 113 K. Source of material A mixture of 1-N-methyl-spiro[2.3']oxindole-spiro[3.2'']5''-(4chloro)benzylidenecyclopentanone-4-(4-chloro)phenylpyrrolidine (1 mmol), isatin (1 mmol) and sarcosine (1 mmol) was refluxed in methanol (60 ml) until the disappearence of the starting material as evidenced by the TLC. After the reaction was over, the solvent was removed in vacuo and the residue was treated by column chromatography (silica gel, petroleum ether/ ethylacetate, 5:1) to give the title compound. 20 mg of the title compound was dissolved in 15 ml methanol/water mixture. The solution was kept at room temperature for 15 d by natural evaporation to give colorless single crystals suitable for X-ray diffraction analysis. Experimental details The H atoms bound to C were included in the riding model approximation with d(C—H) = 0.95 0.99 A and Uiso(H) = 1.2 Ueq(C). H2Abound toNwas found in difference Fouriermap and was refinedwithUiso(H) = 1.2Ueq(N). Thewater molecule is disordered and which H atoms were not located. Discussion The molecule of title compound revealed the presence of a ring system with spiro junctions at atoms C15, C17 and C20. It consists of a 2-oxindole ring, an envelope pyrrolidine ring, an envelope isoxazoline ring and a twist-shaped cyclopentane ring. There exists a trispiro rings in the molecule which consists of a 2oxindole ring, a pyrrolidine ring, an isoxazoline ring and a cyclopentane ring. The pyrrolidine ring (N3/C20/C17/C30/C29) has an envelope conformation. C20/C17/C30/C29 part is nearly planar with the mean deviation from this plane is 0.01345(3)A. The N3 lies 0.5845(3) A from the C20/C17/C30/C29 plane in pyrrolidine ring, forming the flap of the envelope. The dihedral angle between the C20/N3/C29 plane and the C20/C17/C30/C29 mean plane is 42.7(4)°. The dihedral angle between phenyl plane (C31/C32/C33/C34/C35/C36) and C20/C17/C30/C29 plane is 98.6(3)°. In 2-oxindole ring (N2/C26/C25/C24/C23/C22/C21/ C27), the N2/C26/C25/C24/C23/C22/C21 part is nearly planar with the mean deviation from this plane of 0.0384(3)A. The C27 lies 0.2390(3)A from theN2/C26/C25/C24/C23/C22/C21 plane. The dihedral angle between N2/C26/C25/C24/C23/C22/C21 mean plane and C20/C17/C30/C29 plane in pyrrolidine ring is 86.3(3)°. The isoxazoline ring (O1/N1/C7/C8/C15)) was also an envelope conformation. O1/N1/C7/C8 form nearly a plane with mean deviation from this plane of 0.0007(3) A. The C15 lies 0.3065(3) A from the O1/N1/C7/C8 plane in isoxazoline ring, forming the flap of the envelope. The dihedral angle between the O1/N1/C7/C8 plane and the phenyl plane (C9/C10/C11/C12/ C13/C14) is 94.5(4)°. 34 Z. Kristallogr. NCS 225 (2010) 34-36 / DOI 10.1524/ncrs.2010.0013 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless plate, size 0.06 × 0.12 × 0.16 mm Wavelength: Mo K+ radiation (0.71073 A) .: 3.88 cm−1 Diffractometer, scan mode: RIGAKU SATURN CCD , #\% 2,max: 50° N(hkl)measured, N(hkl)unique: 22901, 5525 Criterion for Iobs, N(hkl)gt: Iobs > 2 ((Iobs), 5024 N(param)refined: 474 Programs: SHELXS-97 [1], SHELXL-97 [2], SHELXTL [3] Table 1. Data collection and handling.

Diethyl 1-acetyl-4′-(4-chlorophenyl)-5′-(4-nitrophenyl)-2-oxospiro[indoline-3,3′-pyrrolidine]-2′,2′-dicarboxylate

In the title compound, C31H28ClN3O8, the pyrrolidine ring exhibits an envelope conformation, with the spiro C atom located at the flap position. A spiro junction links the oxindole ring system and the pyrrolidine ring. The planar oxindole ring system is twisted with respect to the nitro­benzene and chloro­benzene rings, with dihedral angles of 62.34 (11) and 75.93 (9)°, respectively. In the crystal, a weak C—H⋯O interaction links the molecules into chains and two intramolecular C—H⋯O close contacts are seen.

Rac-(4R,17S,18R,26R)-Ethyl 4′-methoxycarbonyl-5′′-(4-methoxyphenyl)-1′-methyl-2,3′′-dioxo-2′′,3′′-dihydroindoline-3-spiro-2′-pyrrolidine-3′-spiro-2′′-thiazolo[3,2-a]pyrimidine-6′′-carboxylate

In the title compound, C30H30N4O7S, the two spiro junctions link a planar 2-oxindole ring [with a mean deviation from the plane of 0.0319 (3) Å, a pyrrolidine ring in an envelope conformation and a thia­zolo[3,2-a]pyrimidine system. Two mol­ecules are connected into a dimer by two N—H⋯O hydrogen bonds, forming an R 2 2(8) graph-set motif. The title compound has four stereogenic centers and appears as a racemic mixture of one single diastereoisomer (RSRR/SRSS).

Synthesis and characterisation of six Fe(II or III), Co(II) or Zr(IV) complexes containing the ligand [CH(SiMe 2R)P(Ph) 2NSiMe 3] − (R = Me, NEt 2) and of [Co{N(SiMe 3)C(Ph)C(H)P(Ph) 2NSiMe 3} 2

The C, N-(trimethylsilyliminodiphenylphosphoranyl)silylmethylmetal complexes [Fe( L) 2] ( 3), [Co( L) 2] ( 4), [ZrCl 3( L)]·0.83CH 2Cl 2 ( 5), [Fe( L) 3] ( 6), [Fe( L′) 2] ( 7) and [Co( L′) 2] ( 8) have been prepared from the lithium compound Li[CH(SiMe 2R)P(Ph) 2NSiMe 3] [ 1a, (R = Me) {≡ Li( L)}; 1b, (R = NEt 2) {≡ Li( L′)}] and the appropriate metal chloride (or for 7, FeCl 3). From Li[N(SiMe 3)C(Ph)C(H)P(Ph) 2NSiMe 3] [≡ Li( L″)] ( 2), prepared in situ from Li( L) ( 1a) and PhCN, and CoCl 2 there was obtained bis(3-trimethylsilylimino- diphenylphosphoranyl-2-phenyl- N-trimethylsilyl-1-azaallyl- N, N ′)cobalt(II) ( 9). These crystalline complexes 3– 9 were characterised by their mass spectra, microanalyses, high spin magnetic moments (not 5) and for 5 multinuclear NMR solution spectra. The X-ray structure of 3 showed it to be a pseudotetrahedral bis(chelate), the iron atom at the spiro junction.

2'-Methyl-2'-nitro-1'-phenyl-2',3',5',6',7',7a'-hexa-hydro-spiro-[indoline-3,3'-1'H-pyrrolizin]-2-one.

The title compound, C21H21N3O3, was synthesized by a multi-component 1,3-dipolar cyclo­addition of azomethine ylide, derived from isatin and proline by a deca­rboxylative route, and (E)-1-phenyl-2-nitro­propene. In the mol­ecule, the spiro junction links a planar oxindole ring and a pyrrolidine ring in an envelope conformation. The mol­ecular packing is stabilized by an inter­molecular N—H⋯N inter­action of the oxindole and pyrrolizidine rings.

Modulation of Unconventional Fluorescence of Novel Photochromic Perimidine Spirodimers

Fluorescence modulation by a class of photochromic perimidine spirodimers, which exhibit a characteristic fluorescence associated with their photochromic reactions, has been described. Upon irradiation using 365 nm light, these non-fluorescent spiro molecules undergo a thermally-reversible ring opening at their spiro junction resulting in the generation of strong fluorescence. The fluorescing species is distinctly different from both the stable ring-closed and the ring-opened compounds, though it appears to have been formed from and remains in equilibrium with the photochemically generated ring-opened form. While the fluorescing species possesses a narrow absorption band with its maximum centered at 500 nm, the ring-opened form exhibits a broad absorption across the visible region with two maxima centered at 410 and 650 nm, respectively. After initiating the photochromic reactions in these molecules using 365 nm light, purely photochemically-controlled fluorescence modulation can be carried out using two wavelengths in the visible region, that is, 500 and 700 nm, while the equilibrium concentration of the ring-opened form and the fluorescing species is controlled. Fluorescence modulation is attained also by controlling the ratio of the ring-closed and ring-opened forms by photochemical ring-opening and thermal ring-closing reactions. The study on the effect of substitution of these molecules suggests that by extending the conjugation of the perimidine core in the ring-opened form the molecule is rendered non-fluorescent and hence it can be assumed that the perimidine core forms the fluorescing entity of the molecule.

1′-Methyl-4′-(1-naphthyl)-1H-indole-3-spiro-2′-pyrrolidine-3′-spiro-2′′-thiazolo[3,2-a]benzimidazole-2(3H),3′′(2′′H)-dione

In the title compound, C30H22N4O2S, two spiro junctions link a planar 2-oxoindole ring, a pyrrolidine ring and a thiazolo[3,2-a][1,3]benzimidazol-3-one system. Molecules form dimers connected by N—H...N hydrogen bonds.

1′-Benzyl-1-(2,4-dimethoxyphenyl)-3-phenoxyspiro[azetidine-2,3′(3H)-indole]-2′,4(1H)-dione

The title compound, C31H26N2O5, is a compound with a spiro junction between β-lactam and isatin ring systems. Its four- and five-membered rings are nearly planar, with maximum deviations of −0.020 (1) and 0.050 (1) Å for their carbonyl C atoms, respectively. The dihedral angle between these two rings is 86.44 (5)°. The crystal structure is stabilized by intra­molecular C—H⋯O hydrogen-bonding and van der Waals inter­actions.

Crystal Structure of Acenaphthene-1'-one-spiro[2'.3]-[4-ethoxycarbonyl]-N-methyl-pyrrolidine-spiro[2.2"]-acenaphthene-1"-one

In the title compound, C30H23NO4, the molecule includes two spiro junctions connecting acenaphthene rings and the pyrrolidine moiety. The acenaphthene ring atoms (C2, C7-C17) and (C3, C18-C28) make dihedral angles of 87.0(1) and 81.3(1)°, respectively, with the pyrrolidine ring system. The pyrrolidine ring exhibits an envelope conformation. In the crystal, packing is stabilized by C-H…π and π-π interactions.