N,N′-Bis(2,2,3,3,4,4,4-hepta­fluoro­butyl)naphthalene-1,4:5,8-tetra­carboximide

Shukla, D.; Rajeswaran, M.; Ahearn, W.G.; Meyer, D.M.

doi:10.1107/S1600536808036738

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 12| December 2008| Page o2327

doi:10.1107/S1600536808036738

Open

access

N,N′-Bis(2,2,3,3,4,4,4-heptafluorobutyl)naphthalene-1,4:5,8-tetracarboximide

Deepak Shukla,^a Manju Rajeswaran,^a ^* Wendy G. Ahearn ^a and Dianne M. Meyer ^a

^aEastman Kodak Company, Rochester, NY 14650-2106, USA
^*Correspondence e-mail: manju.rajeswaran@kodak.com

(Received 30 October 2008; accepted 7 November 2008; online 13 November 2008)

The title molecule, C₂₂H₈F₁₄N₂O₄, lies across a crystallographic inversion center with the naphthalene diimide core essentially planar (mean deviation from plane is 0.0583 Å). The CF₂ groups in the perfluorobutyl chains are in an energetically favorable all trans conformation. In the crystal structure, molecules are packed in slightly displaced layers so that the side chains overlap the aromatic naphthalene diimide rings, thus minimizing any possible π–π overlap.

Related literature

For general background on the semic-conducting properties and use of this class of materials in organic thin-film transistor applications, see: Chesterfield et al. (2004a ,b ); Facceti et al. (2008 ); Jones et al. (2004 ); Katz et al. (2000a ,b ); Kazmaier & Hoffmann (1994 ); Klebe et al. (1989 ); Shukla et al. (2008 ); Wurthner (2004 ).

Experimental

Crystal data

C₂₂H₈F₁₄N₂O₄
M_r = 630.30
Triclinic, $[P \overline 1]$
a = 5.1910 (5) Å
b = 10.1459 (12) Å
c = 11.5988 (15) Å
α = 66.693 (4)°
β = 79.064 (4)°
γ = 89.115 (7)°
V = 549.64 (11) Å³
Z = 1
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 293 (2) K
0.15 × 0.10 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: none
3049 measured reflections
2094 independent reflections
909 reflections with I > 2σ(I)
R_int = 0.057

Refinement

R[F² > 2σ(F²)] = 0.067
wR(F²) = 0.223
S = 0.93
2094 reflections
190 parameters
H-atom parameters constrained
Δρ_max = 0.23 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and Materials Studio (Accelrys, 2002 ); software used to prepare material for publication: publCIF (Westrip, 2008 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808036738/lh2728sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808036738/lh2728Isup2.hkl

checkCIF report

Comment top

Amongst n-type semiconductors used in organic thin film transistors, perylene diimides (PDIs) and naphthalene diimides (NDIs) have attracted considerable attention. The π -orbital wavefunctions in these systems form nodes at the two nitrogen positions in the imide rings. Indeed, it has been shown that semiconducting properties and device performance of these materials is very sensitive to the nature of substituents on the diimide nitrogen atoms. The title compound N,N'-Bis(1H,1H-perfluorobutyl) naphthalene- 1,4,5,8-tetracarboxylic acid diimide(I) has been shown to exhibit good n-type semiconducting behavior and OTFTs made incorporating I can be operated in air. The latter property has been ascribed to the denser packing of fluorinated alkyl chains in thin film.

Naphthalene diimide (NDI) and perylene diimide (PDI) based systems have been studied extensively (Chesterfield, et al., 2004a; Chesterfield et al., 2004b; Facceti et al., 2008; Jones, et al., 2004; Katz, et al., 2000a; Katz, et al., 2000b). We report here the structure of the title diimide molecule (I) (Fig. 1 and Fig 2). In the crystal structure, molecules are packed in slightly displaced layers so that the side chains overlap the aromatic naphthalene diimide rings, thus resulting in minimizing any possible π-π overlap (Fig .3).

Related literature top

For general background on the semic-conducting properties and use of this class of materials in organic thin-film transistor applications, see: Chesterfield et al. (2004a,b); Facceti et al. (2008); Jones et al. (2004); Katz et al. (2000a,b); Kazmaier & Hoffmann (1994); Klebe et al. (1989); Shukla et al. (2008); Wurthner (2004).

Experimental top

The method described in Katz et al., 2000a, was followed for preparation of the title compound (I). Crystals of title (I) appeared during powder X-ray diffraction data collection of the dry lot sample. The crystals were weakly diffracting, but we were unable to get better quality crystals. Diffraction data were collected on various crystals, and the results of structure determination using best data set results are reported here.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Materials Studio (Accelrys, 2002); software used to prepare material for publication: publCIF (Westrip, 2008).

Figures top

	Fig. 1. Molecular structure of the title compound, with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are omitted for clarity.
	Fig. 2. A diagram illustrating planar naphthalene diimide core and trans configuration of perfluorobutyl chains on diiimide N atoms.
	Fig. 3. Unit cell packing showing layered structure.

N,N'-Bis(2,2,3,3,4,4,4-heptafluorobutyl)naphthalene-1,4:5,8- tetracarboximide top

Crystal data top

C₂₂H₈F₁₄N₂O₄	Z = 1
M_r = 630.30	F(000) = 312
Triclinic, P1	D_x = 1.904 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.1910 (5) Å	Cell parameters from 4558 reflections
b = 10.1459 (12) Å	θ = 1.0–26.7°
c = 11.5988 (15) Å	µ = 0.21 mm⁻¹
α = 66.693 (4)°	T = 293 K
β = 79.064 (4)°	Needle, pink
γ = 89.115 (7)°	0.15 × 0.10 × 0.05 mm
V = 549.64 (11) Å³

Data collection top

Nonius KappaCCD diffractometer	909 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.057
Graphite monochromator	θ_max = 26.6°, θ_min = 4.1°
Detector resolution: 9 pixels mm^-1	h = −6→6
ϕ and ω scans	k = −12→11
3049 measured reflections	l = −14→12
2094 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.067	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.223	H-atom parameters constrained
S = 0.93	w = 1/[σ²(F_o²) + (0.1P)² + 0.3623P] where P = (F_o² + 2F_c²)/3
2094 reflections	(Δ/σ)_max < 0.001
190 parameters	Δρ_max = 0.23 e Å⁻³
0 restraints	Δρ_min = −0.23 e Å⁻³

Crystal data top

C₂₂H₈F₁₄N₂O₄	γ = 89.115 (7)°
M_r = 630.30	V = 549.64 (11) Å³
Triclinic, P1	Z = 1
a = 5.1910 (5) Å	Mo Kα radiation
b = 10.1459 (12) Å	µ = 0.21 mm⁻¹
c = 11.5988 (15) Å	T = 293 K
α = 66.693 (4)°	0.15 × 0.10 × 0.05 mm
β = 79.064 (4)°

Data collection top

Nonius KappaCCD diffractometer	909 reflections with I > 2σ(I)
3049 measured reflections	R_int = 0.057
2094 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.067	0 restraints
wR(F²) = 0.223	H-atom parameters constrained
S = 0.93	Δρ_max = 0.23 e Å⁻³
2094 reflections	Δρ_min = −0.23 e Å⁻³
190 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
F1	0.1050 (6)	0.4145 (3)	0.7561 (3)	0.0814 (11)
F2	0.1713 (6)	0.5174 (3)	0.8788 (3)	0.0828 (12)
F3	0.5849 (6)	0.3623 (4)	0.9393 (3)	0.0873 (12)
F4	0.5572 (7)	0.2684 (3)	0.8049 (3)	0.0883 (12)
F5	0.3622 (7)	0.0974 (4)	1.0537 (3)	0.0931 (12)
F6	0.0806 (7)	0.2472 (4)	1.0654 (4)	0.1050 (15)
F7	0.0800 (9)	0.1477 (4)	0.9346 (4)	0.1234 (17)
O1	0.2493 (8)	0.6081 (4)	0.4924 (4)	0.0742 (12)
O2	0.5194 (8)	0.8024 (4)	0.7439 (4)	0.0725 (12)
N1	0.3566 (7)	0.6967 (4)	0.6298 (4)	0.0484 (11)
C1	0.2325 (10)	0.7037 (5)	0.5308 (5)	0.0528 (14)
C2	0.0799 (9)	0.8305 (5)	0.4790 (5)	0.0467 (12)
C3	−0.0607 (10)	0.8401 (5)	0.3865 (5)	0.0562 (14)
H3	−0.0557	0.7679	0.3559	0.067*
C4	−0.2109 (10)	0.9584 (5)	0.3386 (5)	0.0541 (14)
H4	−0.3058	0.9637	0.2767	0.065*
C5	0.0752 (9)	0.9387 (5)	0.5243 (4)	0.0440 (12)
C6	0.2199 (9)	0.9345 (5)	0.6184 (5)	0.0482 (13)
C7	0.3779 (10)	0.8079 (5)	0.6691 (5)	0.0523 (14)
C8	0.4892 (9)	0.5658 (5)	0.6912 (5)	0.0537 (14)
H8A	0.6355	0.5891	0.7224	0.064*
H8B	0.5580	0.5257	0.6292	0.064*
C9	0.2958 (10)	0.4562 (6)	0.8023 (5)	0.0544 (14)
C10	0.4188 (10)	0.3238 (5)	0.8827 (5)	0.0550 (14)
C11	0.2281 (13)	0.2022 (6)	0.9871 (6)	0.0676 (16)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F1	0.061 (2)	0.082 (2)	0.086 (2)	−0.0057 (16)	−0.0279 (18)	−0.0114 (19)
F2	0.091 (2)	0.063 (2)	0.074 (2)	0.0213 (17)	0.0167 (18)	−0.0222 (18)
F3	0.074 (2)	0.098 (3)	0.083 (3)	−0.0005 (18)	−0.0340 (18)	−0.021 (2)
F4	0.108 (3)	0.077 (2)	0.070 (2)	0.0396 (19)	−0.0012 (19)	−0.0278 (19)
F5	0.107 (3)	0.071 (2)	0.078 (2)	0.025 (2)	−0.018 (2)	−0.0064 (19)
F6	0.101 (3)	0.087 (3)	0.082 (3)	0.023 (2)	0.026 (2)	−0.007 (2)
F7	0.147 (4)	0.081 (3)	0.125 (4)	−0.039 (3)	−0.057 (3)	−0.008 (3)
O1	0.095 (3)	0.070 (3)	0.073 (3)	0.031 (2)	−0.024 (2)	−0.042 (2)
O2	0.079 (3)	0.067 (3)	0.080 (3)	0.0131 (19)	−0.038 (2)	−0.029 (2)
N1	0.054 (2)	0.040 (2)	0.051 (3)	0.0061 (18)	−0.010 (2)	−0.018 (2)
C1	0.059 (3)	0.046 (3)	0.052 (3)	0.009 (3)	−0.006 (3)	−0.021 (3)
C2	0.049 (3)	0.048 (3)	0.044 (3)	0.003 (2)	−0.002 (2)	−0.023 (3)
C3	0.068 (3)	0.051 (3)	0.057 (3)	0.006 (3)	−0.015 (3)	−0.028 (3)
C4	0.064 (3)	0.058 (3)	0.047 (3)	0.005 (3)	−0.016 (2)	−0.026 (3)
C5	0.045 (3)	0.044 (3)	0.038 (3)	0.001 (2)	−0.002 (2)	−0.014 (2)
C6	0.046 (3)	0.051 (3)	0.041 (3)	0.003 (2)	−0.003 (2)	−0.014 (3)
C7	0.051 (3)	0.052 (3)	0.044 (3)	0.000 (2)	−0.004 (3)	−0.012 (3)
C8	0.050 (3)	0.055 (3)	0.051 (3)	0.009 (2)	−0.010 (2)	−0.017 (3)
C9	0.053 (3)	0.056 (3)	0.057 (4)	0.010 (3)	−0.010 (3)	−0.026 (3)
C10	0.060 (3)	0.058 (3)	0.054 (3)	0.014 (3)	−0.011 (3)	−0.031 (3)
C11	0.085 (4)	0.056 (4)	0.058 (4)	0.003 (3)	−0.024 (4)	−0.015 (3)

Geometric parameters (Å, º) top

F1—C9	1.357 (6)	C2—C5	1.389 (6)
F2—C9	1.341 (6)	C3—C4	1.402 (7)
F3—C10	1.325 (6)	C3—H3	0.9300
F4—C10	1.338 (6)	C4—C6ⁱ	1.360 (7)
F5—C11	1.321 (6)	C4—H4	0.9300
F6—C11	1.294 (7)	C5—C6	1.425 (6)
F7—C11	1.314 (6)	C5—C5ⁱ	1.435 (9)
O1—C1	1.213 (6)	C6—C4ⁱ	1.360 (7)
O2—C7	1.223 (6)	C6—C7	1.491 (7)
N1—C7	1.387 (6)	C8—C9	1.522 (7)
N1—C1	1.398 (6)	C8—H8A	0.9700
N1—C8	1.467 (6)	C8—H8B	0.9700
C1—C2	1.477 (7)	C9—C10	1.513 (7)
C2—C3	1.380 (7)	C10—C11	1.539 (8)

C7—N1—C1	124.8 (4)	N1—C8—C9	109.7 (4)
C7—N1—C8	117.3 (5)	N1—C8—H8A	109.7
C1—N1—C8	117.8 (4)	C9—C8—H8A	109.7
O1—C1—N1	120.4 (5)	N1—C8—H8B	109.7
O1—C1—C2	123.0 (5)	C9—C8—H8B	109.7
N1—C1—C2	116.6 (5)	H8A—C8—H8B	108.2
C3—C2—C5	120.2 (5)	F2—C9—F1	105.5 (4)
C3—C2—C1	119.6 (5)	F2—C9—C10	108.6 (4)
C5—C2—C1	120.2 (5)	F1—C9—C10	108.7 (4)
C2—C3—C4	120.1 (5)	F2—C9—C8	110.1 (4)
C2—C3—H3	119.9	F1—C9—C8	109.2 (4)
C4—C3—H3	119.9	C10—C9—C8	114.3 (4)
C6ⁱ—C4—C3	120.9 (5)	F3—C10—F4	107.7 (4)
C6ⁱ—C4—H4	119.6	F3—C10—C9	109.0 (4)
C3—C4—H4	119.6	F4—C10—C9	108.5 (4)
C2—C5—C6	122.3 (5)	F3—C10—C11	107.7 (5)
C2—C5—C5ⁱ	120.6 (6)	F4—C10—C11	107.2 (5)
C6—C5—C5ⁱ	117.2 (6)	C9—C10—C11	116.4 (5)
C4ⁱ—C6—C5	121.0 (5)	F6—C11—F7	109.6 (6)
C4ⁱ—C6—C7	121.4 (5)	F6—C11—F5	108.2 (5)
C5—C6—C7	117.7 (5)	F7—C11—F5	107.3 (5)
O2—C7—N1	121.5 (5)	F6—C11—C10	111.6 (5)
O2—C7—C6	120.7 (5)	F7—C11—C10	110.2 (5)
N1—C7—C6	117.8 (5)	F5—C11—C10	109.8 (5)

C7—N1—C1—O1	171.2 (4)	C4ⁱ—C6—C7—N1	173.8 (4)
C8—N1—C1—O1	−4.5 (7)	C5—C6—C7—N1	−5.4 (6)
C7—N1—C1—C2	−9.8 (7)	C7—N1—C8—C9	95.1 (5)
C8—N1—C1—C2	174.5 (4)	C1—N1—C8—C9	−88.9 (5)
O1—C1—C2—C3	2.8 (8)	N1—C8—C9—F2	−50.4 (6)
N1—C1—C2—C3	−176.1 (4)	N1—C8—C9—F1	65.0 (6)
O1—C1—C2—C5	−178.0 (5)	N1—C8—C9—C10	−173.0 (5)
N1—C1—C2—C5	3.1 (7)	F2—C9—C10—F3	−59.0 (5)
C5—C2—C3—C4	−0.6 (7)	F1—C9—C10—F3	−173.3 (4)
C1—C2—C3—C4	178.6 (4)	C8—C9—C10—F3	64.4 (6)
C2—C3—C4—C6ⁱ	0.4 (8)	F2—C9—C10—F4	−176.0 (4)
C3—C2—C5—C6	−179.1 (4)	F1—C9—C10—F4	69.7 (5)
C1—C2—C5—C6	1.7 (7)	C8—C9—C10—F4	−52.6 (6)
C3—C2—C5—C5ⁱ	0.0 (8)	F2—C9—C10—C11	63.0 (6)
C1—C2—C5—C5ⁱ	−179.2 (5)	F1—C9—C10—C11	−51.3 (7)
C2—C5—C6—C4ⁱ	−179.8 (4)	C8—C9—C10—C11	−173.5 (5)
C5ⁱ—C5—C6—C4ⁱ	1.1 (8)	F3—C10—C11—F6	65.9 (6)
C2—C5—C6—C7	−0.6 (7)	F4—C10—C11—F6	−178.4 (5)
C5ⁱ—C5—C6—C7	−179.7 (5)	C9—C10—C11—F6	−56.8 (7)
C1—N1—C7—O2	−169.7 (5)	F3—C10—C11—F7	−172.1 (5)
C8—N1—C7—O2	6.0 (7)	F4—C10—C11—F7	−56.4 (6)
C1—N1—C7—C6	11.0 (7)	C9—C10—C11—F7	65.2 (7)
C8—N1—C7—C6	−173.3 (4)	F3—C10—C11—F5	−54.1 (7)
C4ⁱ—C6—C7—O2	−5.5 (7)	F4—C10—C11—F5	61.6 (6)
C5—C6—C7—O2	175.3 (4)	C9—C10—C11—F5	−176.8 (5)

Symmetry code: (i) −x, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₂₂H₈F₁₄N₂O₄
M_r	630.30
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	5.1910 (5), 10.1459 (12), 11.5988 (15)
α, β, γ (°)	66.693 (4), 79.064 (4), 89.115 (7)
V (Å³)	549.64 (11)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	0.21
Crystal size (mm)	0.15 × 0.10 × 0.05

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	3049, 2094, 909
R_int	0.057
(sin θ/λ)_max (Å⁻¹)	0.630

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.067, 0.223, 0.93
No. of reflections	2094
No. of parameters	190
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.23, −0.23

Computer programs: COLLECT (Nonius, 2000), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXTL (Sheldrick, 2008) and Materials Studio (Accelrys, 2002), publCIF (Westrip, 2008).

Acknowledgements

The authors thank Dr Thomas R. Welter and Thomas N. Blanton of Eastman Kodak Company for their help in the preparation of this material and crystals of this material, respectively.

References

Accelrys (2002). Materials Studio. Accelrys Inc., San Diego, California. Google Scholar
Chesterfield, R. J., McKeen, J. C., Newman, C. R., Ewbank, P. C., da SilvaFilho, D. A., Brédas, J. L., Miller, L. L., Mann, K. R. & Frisbie, C. D. (2004a). J. Phys. Chem. B, 108, 19281–19292. Web of Science CrossRef CAS Google Scholar
Chesterfield, R. J., McKeen, J. C., Newman, C. R., Frisbie, C. D., Ewbank, P. C., Mann, K. R. & Miller, L. L. (2004b). Appl. Phys. Lett. 95, 6396–6405. CAS Google Scholar
Facceti, A., Yoon, M.-H. & Marks, T. J. (2008). Adv. Mater. 17, 1705–1725. Google Scholar
Jones, B. A., Ahrens, M. J., Yoon, M.-H., Facchetti, A., Marks, T. J. & Wasielewski, M. R. (2004). Angew. Chem. Int. Ed. 43, 6363–6366. Web of Science CSD CrossRef CAS Google Scholar
Katz, H. E., Johnson, J., Lovinger, A. J. & Li, W. (2000a). J. Am. Chem. Soc. 122, 7787–7792. Web of Science CrossRef CAS Google Scholar
Katz, H. E., Lovinger, A. J., Johnson, J., Kloc, C., Siegrist, T., Li, W., Lin, Y.-Y. & Dodabalapur, A. (2000b). Nature (London), 404, 478–481. Web of Science CrossRef PubMed CAS Google Scholar
Kazmaier, P. M. & Hoffmann, R. (1994). J. Am. Chem. Soc. 116, 9684–9691. CrossRef CAS Web of Science Google Scholar
Klebe, G., Graser, F., Hädicke, E. & Berndt, J. (1989). Acta Cryst. B45, 69–77. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Shukla, D., Nelson, S. F., Freeman, D. C., Rajeswaran, M., Ahearn, W. G., Meyer, D. M. & Carey, J. T. (2008). Chem. Mater. In the press. Google Scholar
Westrip, S. P. (2008). publCIF. In preparation. Google Scholar
Wurthner, F. (2004). Chem. Commun. pp. 1564–1579. Web of Science CrossRef Google Scholar