Synthesis and Complexation Behavior of Diaza-18-crown-6 Carrying Two Pyrenylmethyl Groups

Abstract

N,N′-Bis(1-pyrenylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (1) and N-(1-pyrenylmethyl)-1,4,7,10,13-pentaoxa-16-azacyclooctadecane (2) were synthesized and found to display unique photophysical properties in the presence of the guest-metal salts. The binding of metal ions to the diazacrown ether 1 cavity inhibited the exciplex formation and changed the distance between two pyrenyl groups. This caused not only an emission-intensity enhancement, but also a large change in the monomer/excimer fluorescence-intensity ratio. The change resulted from the coordinated structure and exchange process between the free host 1 and its metal salt complex in the ground state.

Crystal Structures of Thiobarbiturate with N-Phenylalkyl Group and Its Photocyclization Product

“…The H O distance H11 O1 iv : 2.655 Å, symmetry code: iv 1-x, 1/2 y, 1/2-z is similar to those of 7,16-bis 1-pyrenylmethyl -1,4,10,13-tetraoxa-7,16-diazacyclooctadecene 2.58 Å 21,22 and N,N -di tropon-2-yl piperazine 2.50-2.64 Å 23 . These C1-N1-C2-N2 34.98 (13) C1-N1-C2-C3 149.07 (11) C2-N1-C1-C8 5.72 (14) C2-N2-C6-C5 51.71 (13) C6-N2-C2-N1 149.98 (9) C6-N2-C2-C3 26.15 (14) C2-N2-C7-C8 3.75 (15) C7-N2-C2-N1 36.19 (14) C7-N2-C2-C3 147.68 (11) C6-N2-C7-C8 169.80 (10) C7-N2-C6-C5 122.11 (11) N1-C1-C8-C7 43.92 (13) N1-C2-C3-C4 170.34 (9) N2-C2-C3-C4 5.29 (16) C2-C3-C4-C5 12.57 (15) C3-C4-C5-C6 38.82 (13) C4-C5-C6-N2 57.29 (12) N2-C7-C8-C1 42.71 (14) C N contacts and C-H S and C-H O interactions help to stabilize the crystal packing.…”

“…4 and give in Table 4. The H5 O1 i , H15 O2 ii , H7 O2 iii , and H12 O1 iv i 1-x, y-1/2,1/2-z; ii 1-x, y 1/2,1/2-z; iii 2-x, 1/2 y, 1/2-z; and iv x, 1/2-y, z-1/2 distances are close to those of 7,16-bis 1-pyrenylmethyl -1,4,10,13-tetraoxa-7,16-diazacyclooctadecene 2.58 Å 21,22 and N,N -di tropon-2-yl piperazine 2.50-2.64 Å 23 . The intermolecular C-H O interactions help to stabilize the crystal packing.…”

Crystal Structure and Complexation and Fluorescence Behaviors of 1,4-Bis (9-anthracenylmethyl) piperazine

“…6 allowed us to determine the association constants K by a non-linear curve-fi tting method 8,17 Zn 2 . The comparison of the selectivity orders of compounds 1-3 confi rms that the size of the azamacrocycle and the electronic properties of the aromatic pendants may fi nely control the selectivity of the host toward the guest cations.…”

“…De Silva et al 1,4,6 have created a photoinduced electron transfer PET fl uoroionophore consisting of an azacrown ether with an anthryl group. We have reported that multi-donor-spacer-multi-acceptor systems [7][8][9][10][11][12][13] such as diaza-18-crown-6 1 and diaza-12-crown-4 2 ethers, carrying two 9-anthrylmethyl groups, have a higher fluorescence switch-on ability for guest cation complexation than those of the corresponding monoazacrown derivatives Scheme 1 . Piperazine is widely used as a chelate.…”

“…The number of equivalent cations added was then plotted against the emission-intensity change at 418 nm excited at 367 nm . The association constants K were determined by the curve-fi tting method that has been used in previous studies 8,17 .…”