The peptide NCbz-Val-Tyr-OMe and aromatic [pi]-[pi] interactions

The peptide N-benzyloxycarbonyl-L-valyl-L-tyrosine methyl ester or NCbz-Val-Tyr-OMe (where NCbz is N-benzyloxycarbonyl and OMe indicates the methyl ester), C₂₃H₂₈N₂O₆, has an extended backbone conformation. The aromatic rings of the Tyr residue and the NCbz group are involved in various attractive intra- and intermolecular aromatic [pi]-[pi] interactions which stabilize the conformation and packing in the crystal structure, in addition to N-H...O and O-H...O hydrogen bonds. The aromatic [pi]-[pi] interactions include parallel-displaced, perpendicular T-shaped, perpendicular L-shaped and inclined orientations.

S1. Experimental

S1.1. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

S2. Results and discussion

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012) and Mercury (Macrae et al., 2008).

Figures

N-Benzyloxycarbonyl-L-valyl-L-tyrosine methyl ester

Crystal data

C23H28N2O6	Z = 2
Mr = 428.47	F(000) = 456
Monoclinic, P21	Dx = 1.219 Mg m^−3
a = 11.2986 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 4.8997 (1) Å	µ = 0.09 mm^−1
c = 21.6179 (5) Å	T = 293 K
β = 102.636 (1)°	Rod-shaped, colourless
V = 1167.78 (5) Å^3	0.6 × 0.1 × 0.1 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer	3237 independent reflections
Radiation source: fine-focus sealed tube	2636 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
ϕ and ω scans	θmax = 28.3°, θmin = 1.0°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −14→15
Tmin = 0.690, Tmax = 0.746	k = −6→5
20229 measured reflections	l = −28→28

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.099	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0484P)^2 + 0.086P] where P = (Fo^2 + 2Fc^2)/3
3237 reflections	(Δ/σ)max < 0.001
348 parameters	Δρmax = 0.19 e Å^−3
1 restraint	Δρmin = −0.12 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
H11	0.8406 (17)	0.396 (6)	0.6252 (9)	0.046 (5)*
H21	1.1716 (17)	0.736 (5)	0.7300 (9)	0.041 (5)*
H12	0.803 (2)	0.901 (7)	0.5663 (11)	0.063 (7)*
H29	1.222 (2)	0.178 (7)	0.7417 (11)	0.072 (8)*
H2	1.036 (2)	0.333 (7)	0.6733 (10)	0.056 (7)*
H23	1.163 (2)	0.658 (8)	0.9483 (14)	0.088 (9)*
H22	1.265 (2)	0.649 (7)	0.8638 (11)	0.074 (7)*
H1	0.767 (2)	0.826 (7)	0.6828 (12)	0.065 (7)*
H28	1.317 (2)	0.389 (6)	0.7784 (10)	0.063 (6)*
H25	0.928 (2)	0.084 (7)	0.8658 (12)	0.083 (8)*
H27	1.000 (4)	0.510 (11)	0.991 (2)	0.131 (15)*
H26	1.034 (2)	0.066 (7)	0.7821 (12)	0.073 (7)*
H06	0.748 (3)	0.411 (9)	0.9069 (14)	0.100 (10)*
H02	0.459 (2)	0.828 (7)	0.8023 (12)	0.084 (8)*
H03	0.446 (3)	1.062 (8)	0.8922 (13)	0.089 (9)*
H04	0.564 (2)	0.966 (8)	0.9921 (14)	0.092 (9)*
H05	0.722 (3)	0.640 (9)	1.0026 (16)	0.123 (12)*
O27	0.98374 (17)	0.3639 (5)	0.96680 (8)	0.0709 (5)
C1'	0.97165 (18)	0.6861 (4)	0.65684 (9)	0.0435 (4)
C2A	1.17503 (17)	0.5653 (4)	0.71104 (9)	0.0459 (4)
O08	0.67994 (14)	0.6140 (3)	0.75347 (7)	0.0610 (4)
C0'	0.72530 (18)	0.4894 (4)	0.70802 (10)	0.0510 (5)
N1	0.76971 (17)	0.6712 (4)	0.67350 (9)	0.0508 (4)
O0	0.7234 (2)	0.2449 (3)	0.70082 (10)	0.0828 (6)
O1	0.99586 (15)	0.9310 (3)	0.66112 (9)	0.0675 (5)
N2	1.05297 (15)	0.4953 (4)	0.67900 (8)	0.0480 (4)
O3	1.34464 (14)	0.7713 (5)	0.68479 (7)	0.0729 (5)
C2B	1.22661 (19)	0.3536 (5)	0.76225 (10)	0.0511 (5)
C21	1.16136 (17)	0.3547 (4)	0.81654 (9)	0.0493 (4)
C25	1.0030 (2)	0.1940 (5)	0.86689 (11)	0.0629 (6)
C1A	0.84249 (18)	0.5902 (4)	0.62864 (9)	0.0450 (4)
C24	1.04258 (19)	0.3710 (5)	0.91667 (9)	0.0550 (5)
C26	1.0628 (2)	0.1883 (5)	0.81694 (11)	0.0591 (5)
C1B	0.7961 (2)	0.7072 (6)	0.56177 (11)	0.0586 (5)
C2'	1.25667 (19)	0.5967 (5)	0.66408 (9)	0.0573 (5)
C22	1.1977 (2)	0.5325 (5)	0.86694 (10)	0.0593 (5)
C01	0.60670 (19)	0.5968 (5)	0.84836 (10)	0.0580 (5)
C07	0.6215 (3)	0.4377 (6)	0.79133 (12)	0.0717 (7)
H07A	0.6707	0.2768	0.8043	0.086*
H07B	0.5429	0.3797	0.7670	0.086*
C23	1.1387 (2)	0.5416 (6)	0.91683 (11)	0.0619 (6)
C02	0.5181 (2)	0.7935 (6)	0.84376 (11)	0.0641 (6)
O2	1.2434 (2)	0.4846 (7)	0.61520 (11)	0.1315 (12)
C1G2	0.8743 (2)	0.5984 (8)	0.51842 (11)	0.0818 (8)
H1G1	0.9575	0.6464	0.5353	0.123*
H1G2	0.8480	0.6765	0.4770	0.123*
H1G3	0.8669	0.4033	0.5156	0.123*
C06	0.6816 (2)	0.5442 (7)	0.90719 (13)	0.0776 (7)
C3	1.4270 (2)	0.8256 (10)	0.64360 (13)	0.1006 (12)
H3A	1.4873	0.9545	0.6636	0.151*
H3B	1.3825	0.8995	0.6042	0.151*
H3C	1.4658	0.6589	0.6357	0.151*
C03	0.5047 (3)	0.9362 (6)	0.89716 (15)	0.0740 (7)
C04	0.5793 (3)	0.8795 (7)	0.95488 (14)	0.0817 (8)
C1G1	0.6641 (2)	0.6338 (11)	0.53625 (13)	0.1011 (12)
H1G4	0.6160	0.7043	0.5641	0.152*
H1G5	0.6558	0.4389	0.5336	0.152*
H1G6	0.6370	0.7118	0.4948	0.152*
C05	0.6668 (3)	0.6859 (8)	0.95975 (14)	0.0921 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O27	0.0888 (11)	0.0725 (12)	0.0611 (9)	−0.0017 (10)	0.0375 (8)	0.0006 (9)
C1'	0.0577 (10)	0.0308 (8)	0.0464 (9)	−0.0034 (8)	0.0206 (8)	−0.0041 (7)
C2A	0.0526 (10)	0.0369 (10)	0.0502 (10)	−0.0046 (8)	0.0158 (8)	−0.0072 (9)
O08	0.0852 (10)	0.0394 (8)	0.0714 (9)	−0.0030 (7)	0.0453 (8)	−0.0035 (7)
C0'	0.0590 (11)	0.0373 (10)	0.0630 (11)	0.0017 (9)	0.0269 (9)	−0.0041 (9)
N1	0.0640 (10)	0.0318 (9)	0.0651 (10)	−0.0022 (8)	0.0327 (8)	−0.0070 (8)
O0	0.1264 (15)	0.0334 (8)	0.1108 (14)	−0.0072 (9)	0.0746 (12)	−0.0085 (9)
O1	0.0724 (10)	0.0297 (7)	0.0956 (12)	−0.0073 (7)	0.0081 (9)	−0.0045 (7)
N2	0.0551 (9)	0.0299 (8)	0.0597 (9)	−0.0049 (7)	0.0139 (7)	−0.0043 (7)
O3	0.0606 (8)	0.0961 (14)	0.0667 (9)	−0.0248 (10)	0.0241 (7)	−0.0039 (10)
C2B	0.0547 (11)	0.0463 (11)	0.0554 (11)	0.0011 (9)	0.0184 (9)	−0.0020 (10)
C21	0.0540 (10)	0.0457 (11)	0.0498 (10)	0.0033 (9)	0.0147 (8)	0.0029 (9)
C25	0.0674 (13)	0.0581 (13)	0.0684 (13)	−0.0130 (12)	0.0261 (11)	−0.0050 (12)
C1A	0.0527 (10)	0.0335 (9)	0.0533 (10)	−0.0009 (8)	0.0212 (8)	−0.0050 (8)
C24	0.0622 (11)	0.0573 (12)	0.0490 (10)	0.0063 (10)	0.0197 (9)	0.0062 (10)
C26	0.0686 (12)	0.0548 (12)	0.0577 (12)	−0.0097 (11)	0.0220 (10)	−0.0094 (11)
C1B	0.0648 (12)	0.0553 (13)	0.0569 (12)	0.0015 (11)	0.0160 (9)	−0.0006 (10)
C2'	0.0633 (12)	0.0623 (13)	0.0484 (10)	−0.0075 (11)	0.0167 (9)	−0.0064 (10)
C22	0.0619 (11)	0.0617 (14)	0.0557 (11)	−0.0128 (12)	0.0163 (9)	−0.0037 (11)
C01	0.0640 (12)	0.0545 (12)	0.0631 (12)	−0.0123 (11)	0.0303 (10)	−0.0007 (11)
C07	0.0972 (17)	0.0540 (14)	0.0783 (14)	−0.0151 (13)	0.0503 (13)	−0.0039 (12)
C23	0.0730 (13)	0.0640 (15)	0.0495 (11)	−0.0072 (12)	0.0152 (10)	−0.0080 (11)
C02	0.0680 (13)	0.0610 (14)	0.0653 (13)	−0.0075 (12)	0.0186 (11)	−0.0018 (12)
O2	0.1387 (17)	0.180 (3)	0.0954 (13)	−0.076 (2)	0.0692 (13)	−0.0717 (19)
C1G2	0.0928 (16)	0.103 (2)	0.0564 (12)	0.0038 (17)	0.0320 (12)	0.0050 (15)
C06	0.0709 (14)	0.0800 (19)	0.0824 (17)	0.0041 (15)	0.0175 (13)	0.0022 (16)
C3	0.0730 (15)	0.149 (4)	0.0879 (17)	−0.025 (2)	0.0359 (13)	0.022 (2)
C03	0.0726 (15)	0.0617 (16)	0.0950 (19)	−0.0016 (13)	0.0343 (14)	−0.0104 (14)
C04	0.106 (2)	0.082 (2)	0.0654 (15)	−0.0199 (19)	0.0354 (15)	−0.0187 (15)
C1G1	0.0664 (14)	0.156 (4)	0.0756 (15)	0.004 (2)	0.0047 (12)	−0.010 (2)
C05	0.107 (2)	0.095 (2)	0.0676 (16)	−0.007 (2)	0.0037 (16)	−0.0052 (17)

Geometric parameters (Å, º)

O27—C24	1.390 (2)	C1B—C1G1	1.515 (4)
O27—H27	0.88 (5)	C1B—C1G2	1.519 (3)
C1'—O1	1.230 (2)	C1B—H12	0.96 (3)
C1'—N2	1.325 (3)	C2'—O2	1.171 (3)
C1'—C1A	1.527 (3)	C22—C23	1.388 (3)
C2A—N2	1.443 (3)	C22—H22	0.96 (3)
C2A—C2'	1.521 (3)	C01—C02	1.377 (4)
C2A—C2B	1.536 (3)	C01—C06	1.389 (4)
C2A—H21	0.93 (2)	C01—C07	1.499 (3)
O08—C0'	1.349 (2)	C07—H07A	0.9700
O08—C07	1.445 (3)	C07—H07B	0.9700
C0'—O0	1.207 (3)	C23—H23	0.89 (3)
C0'—N1	1.329 (3)	C02—C03	1.386 (4)
N1—C1A	1.457 (2)	C02—H02	1.01 (3)
N1—H1	0.79 (3)	C1G2—H1G1	0.9600
N2—H2	0.82 (3)	C1G2—H1G2	0.9600
O3—C2'	1.314 (3)	C1G2—H1G3	0.9600
O3—C3	1.446 (3)	C06—C05	1.372 (4)
C2B—C21	1.516 (3)	C06—H06	0.99 (4)
C2B—H29	0.97 (3)	C3—H3A	0.9600
C2B—H28	1.02 (2)	C3—H3B	0.9600
C21—C26	1.382 (3)	C3—H3C	0.9600
C21—C22	1.385 (3)	C03—C04	1.373 (4)
C25—C24	1.378 (3)	C03—H03	0.89 (3)
C25—C26	1.393 (3)	C04—C05	1.357 (5)
C25—H25	1.00 (3)	C04—H04	0.96 (3)
C1A—C1B	1.537 (3)	C1G1—H1G4	0.9600
C1A—H11	0.95 (3)	C1G1—H1G5	0.9600
C24—C23	1.370 (3)	C1G1—H1G6	0.9600
C26—H26	0.96 (3)	C05—H05	1.02 (4)
C24—O27—H27	112 (4)	O2—C2'—O3	123.4 (2)
O1—C1'—N2	122.42 (19)	O2—C2'—C2A	125.3 (2)
O1—C1'—C1A	120.52 (19)	O3—C2'—C2A	111.25 (17)
N2—C1'—C1A	116.98 (17)	C21—C22—C23	121.4 (2)
N2—C2A—C2'	111.04 (16)	C21—C22—H22	114.8 (15)
N2—C2A—C2B	110.97 (17)	C23—C22—H22	123.7 (15)
C2'—C2A—C2B	111.07 (17)	C02—C01—C06	118.9 (2)
N2—C2A—H21	107.2 (12)	C02—C01—C07	121.0 (2)
C2'—C2A—H21	106.9 (12)	C06—C01—C07	120.1 (2)
C2B—C2A—H21	109.5 (12)	O08—C07—C01	107.6 (2)
C0'—O08—C07	115.81 (17)	O08—C07—H07A	110.2
O0—C0'—N1	126.2 (2)	C01—C07—H07A	110.2
O0—C0'—O08	123.0 (2)	O08—C07—H07B	110.2
N1—C0'—O08	110.85 (18)	C01—C07—H07B	110.2
C0'—N1—C1A	121.93 (18)	H07A—C07—H07B	108.5
C0'—N1—H1	117.6 (19)	C24—C23—C22	119.6 (2)
C1A—N1—H1	119.3 (19)	C24—C23—H23	120.8 (19)
C1'—N2—C2A	121.37 (18)	C22—C23—H23	119.6 (19)
C1'—N2—H2	120.3 (17)	C01—C02—C03	120.2 (2)
C2A—N2—H2	118.3 (17)	C01—C02—H02	120.9 (18)
C2'—O3—C3	116.8 (2)	C03—C02—H02	118.8 (17)
C21—C2B—C2A	112.55 (17)	C1B—C1G2—H1G1	109.5
C21—C2B—H29	111.8 (15)	C1B—C1G2—H1G2	109.5
C2A—C2B—H29	107.2 (15)	H1G1—C1G2—H1G2	109.5
C21—C2B—H28	110.8 (12)	C1B—C1G2—H1G3	109.5
C2A—C2B—H28	109.0 (15)	H1G1—C1G2—H1G3	109.5
H29—C2B—H28	105 (2)	H1G2—C1G2—H1G3	109.5
C26—C21—C22	117.83 (19)	C05—C06—C01	120.3 (3)
C26—C21—C2B	122.12 (19)	C05—C06—H06	124.4 (18)
C22—C21—C2B	120.02 (19)	C01—C06—H06	115.1 (17)
C24—C25—C26	119.2 (2)	O3—C3—H3A	109.5
C24—C25—H25	119.1 (16)	O3—C3—H3B	109.5
C26—C25—H25	121.5 (15)	H3A—C3—H3B	109.5
N1—C1A—C1'	106.24 (15)	O3—C3—H3C	109.5
N1—C1A—C1B	113.48 (17)	H3A—C3—H3C	109.5
C1'—C1A—C1B	111.11 (17)	H3B—C3—H3C	109.5
N1—C1A—H11	108.5 (12)	C04—C03—C02	119.8 (3)
C1'—C1A—H11	110.0 (12)	C04—C03—H03	122.7 (19)
C1B—C1A—H11	107.5 (12)	C02—C03—H03	117.4 (19)
C23—C24—C25	120.50 (19)	C05—C04—C03	120.3 (3)
C23—C24—O27	121.8 (2)	C05—C04—H04	120.4 (19)
C25—C24—O27	117.7 (2)	C03—C04—H04	119.1 (18)
C21—C26—C25	121.4 (2)	C1B—C1G1—H1G4	109.5
C21—C26—H26	119.6 (15)	C1B—C1G1—H1G5	109.5
C25—C26—H26	119.0 (15)	H1G4—C1G1—H1G5	109.5
C1G1—C1B—C1G2	110.6 (2)	C1B—C1G1—H1G6	109.5
C1G1—C1B—C1A	111.1 (2)	H1G4—C1G1—H1G6	109.5
C1G2—C1B—C1A	109.0 (2)	H1G5—C1G1—H1G6	109.5
C1G1—C1B—H12	109.2 (15)	C04—C05—C06	120.5 (3)
C1G2—C1B—H12	111.3 (15)	C04—C05—H05	121 (2)
C1A—C1B—H12	105.7 (15)	C06—C05—H05	119 (2)
C07—O08—C0'—O0	−3.6 (4)	N1—C1A—C1B—C1G2	−177.1 (2)
C07—O08—C0'—N1	175.9 (2)	C1'—C1A—C1B—C1G2	63.3 (3)
O0—C0'—N1—C1A	−11.3 (4)	C3—O3—C2'—O2	0.7 (4)
O08—C0'—N1—C1A	169.19 (17)	C3—O3—C2'—C2A	−178.3 (2)
O1—C1'—N2—C2A	1.5 (3)	N2—C2A—C2'—O2	−28.0 (4)
C1A—C1'—N2—C2A	−175.08 (16)	C2B—C2A—C2'—O2	96.0 (3)
C2'—C2A—N2—C1'	−88.1 (2)	N2—C2A—C2'—O3	151.01 (19)
C2B—C2A—N2—C1'	147.81 (18)	C2B—C2A—C2'—O3	−85.0 (2)
N2—C2A—C2B—C21	−66.8 (2)	C26—C21—C22—C23	0.9 (3)
C2'—C2A—C2B—C21	169.21 (17)	C2B—C21—C22—C23	178.9 (2)
C2A—C2B—C21—C26	91.5 (3)	C0'—O08—C07—C01	165.6 (2)
C2A—C2B—C21—C22	−86.5 (2)	C02—C01—C07—O08	75.8 (3)
C0'—N1—C1A—C1'	−110.1 (2)	C06—C01—C07—O08	−105.2 (3)
C0'—N1—C1A—C1B	127.6 (2)	C25—C24—C23—C22	−1.1 (4)
O1—C1'—C1A—N1	−68.0 (2)	O27—C24—C23—C22	177.2 (2)
N2—C1'—C1A—N1	108.56 (19)	C21—C22—C23—C24	0.3 (4)
O1—C1'—C1A—C1B	55.8 (3)	C06—C01—C02—C03	0.1 (4)
N2—C1'—C1A—C1B	−127.56 (19)	C07—C01—C02—C03	179.1 (2)
C26—C25—C24—C23	0.7 (4)	C02—C01—C06—C05	0.2 (4)
C26—C25—C24—O27	−177.6 (2)	C07—C01—C06—C05	−178.8 (3)
C22—C21—C26—C25	−1.3 (3)	C01—C02—C03—C04	−0.5 (4)
C2B—C21—C26—C25	−179.3 (2)	C02—C03—C04—C05	0.5 (5)
C24—C25—C26—C21	0.5 (4)	C03—C04—C05—C06	−0.2 (5)
N1—C1A—C1B—C1G1	−55.1 (3)	C01—C06—C05—C04	−0.2 (5)
C1'—C1A—C1B—C1G1	−174.7 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O0^i	0.79 (3)	2.17 (3)	2.943 (2)	169 (3)
N2—H2···O1^ii	0.82 (3)	2.03 (3)	2.846 (2)	179 (2)
O27—H27···O27^iii	0.88 (5)	1.95 (5)	2.8226 (18)	170 (5)

Symmetry codes: (i) x, y+1, z; (ii) x, y−1, z; (iii) −x+2, y+1/2, −z+2.