Photochemistry and Photophysics of Coordination Compounds

More documents

Recommendations

Info

120 S. Campagna et al. Fig. 1 a Simplified molecular orbital diagram for Ru(II) polypyridine complexes in octahedral symmetry showing the three types of electronic transitions occurring at low energies. b Detailed representation of the MLCT transition in D3 symmetry bitals gives rise to metal-centered (MC) excited states. Ligand-centered (LC) excited states can be obtained by promoting an electron from πL to π ∗ L .All these excited states may have singlet or triplet multiplicity, although spin– orbit coupling causes large singlet–triplet mixing, particularly in MC and MLCT excited states [6, 9–11]. The prototype [Ru(bpy)3] 2+ (Fig. 2), as well as most of the Ru(LL)3 2+ complexes (LL = bidentate polypyridine ligand), exhibits a D3 symmetry [12]. Following Orgel’s notation [13], the π ∗ orbitals may be symmetrical (χ) or Fig. 2 Molecular structural formula of [Ru(bpy)3] 2+
Photochemistry and Photophysics of Coordination Compounds: Ruthenium 121 antisymmetrical (Ψ ) with respect to rotation around the C2 axis retained by each Ru(bpy) unit. A more detailed picture of the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) is shown in Fig. 1b [14–16]. The HOMOs are πMa1(d) and πMe(d), which are mainly localized on the metal; the LUMOs are π ∗ L a2(Ψ )andπ ∗ L e(Ψ ), which are mainly localized on the ligands. The ground state of the complex is a singlet, derived from the πMe(d) 4 πMa1(d) 2 electronic configuration. According to Kasha’s rule, only the lowest excited state and the upper states that can be populated on the basis of the Boltzmann equilibrium distribution may play a role in determining the photochemical and photophysical properties. The MC excited states of d 6 octahedral complexes are strongly displaced with respect to the ground-state geometry along metal–ligand vibration coordinates [17, 18]. When the lowest excited state is MC, it undergoes fast radiationless deactivation to the ground state and/or ligand dissociation reactions (Fig. 3). As a consequence, at room temperature the excited-state lifetime is very short, no luminescence emission can be observed [19], and very rarely bimolecular (or supramolecular) reactions can take place. LC and MLCT excited states are usually not strongly displaced compared to the ground-state geometry. Thus, when the lowest excited state is LC or MLCT (Fig. 3) it does not undergo fast radiationless decay to the ground state and luminescence can usually be observed. The radiative deactivation rate constant is somewhat higher for 3 MLCT than for 3 LC because of the larger spin–orbit coupling effect. For this reason, the 3 LC excited states are longer lived at low temperature in a rigid matrix and the 3 MLCT excited states are more likely to exhibit luminescence at room temperature in fluid solution. Fig. 3 Schematic representation of two limiting cases for the relative positions of 3 MC and 3 LC (or 3 MLCT) excited states
Page 1 and 2:
280 Topics in Current Chemistry Edi
Page 3 and 4:
Photochemistry and Photophysics of
Page 5 and 6:
Volume Editors Prof. Vincenzo Balza
Page 7 and 8:
Topics in Current Chemistry Also Av
Page 9 and 10:
X Preface nation Compounds. The ven
Page 11 and 12:
Contents Photochemistry and Photoph
Page 13 and 14:
Top Curr Chem (2007) 280: 1-36 DOI
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Top Curr Chem (2007) 280: 37-67 DOI
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80: Photochemistry and Photophysics of
Page 81 and 82: 70 N. Armaroli et al. (e.g. catenan
Page 83 and 84: 72 N. Armaroli et al. can be classi
Page 85 and 86: 74 N. Armaroli et al. Fig. 2 Qualit
Page 87 and 88: 76 N. Armaroli et al. Fig. 3 Theblu
Page 89 and 90: 78 N. Armaroli et al. In the CuA mi
Page 91 and 92: 80 N. Armaroli et al. pseudo-rotaxa
Page 93 and 94: 82 N. Armaroli et al. Fig. 11 Relat
Page 95 and 96: 84 N. Armaroli et al. Fig. 13 Absor
Page 97 and 98: 86 N. Armaroli et al. leading to a
Page 99 and 100: 88 N. Armaroli et al. Fig. 18 Trans
Page 101 and 102: 90 N. Armaroli et al. Fig. 20 Ligan
Page 103 and 104: 92 N. Armaroli et al. Fig. 22 Ligan
Page 105 and 106: 94 N. Armaroli et al. tionalized de
Page 107 and 108: 96 N. Armaroli et al. Fig. 24 Absor
Page 109 and 110: 98 N. Armaroli et al. prisingly, PP
Page 111 and 112: 100 N. Armaroli et al. A different
Page 113 and 114: 102 N. Armaroli et al. Cuprous clus
Page 115 and 116: 104 N. Armaroli et al. Fig. 32 Sche
Page 117 and 118: 106 N. Armaroli et al. Fig. 34 A te
Page 119 and 120: 108 N. Armaroli et al. which are va
Page 121 and 122: 110 N. Armaroli et al. Acknowledgem
Page 123 and 124: 112 N. Armaroli et al. 58. Miller M
Page 125 and 126: 114 N. Armaroli et al. 123. Armarol
Page 127 and 128: Top Curr Chem (2007) 280: 117-214 D
Page 129: Photochemistry and Photophysics of
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Top Curr Chem (2007) 280: 215-255 D
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
258 Author Index Volumes 251-280 Be
Page 269 and 270:
260 Author Index Volumes 251-280 Er
Page 271 and 272:
262 Author Index Volumes 251-280 Je
Page 273 and 274:
264 Author Index Volumes 251-280 Me
Page 275 and 276:
266 Author Index Volumes 251-280 Sa
Page 277 and 278:
268 Author Index Volumes 251-280 Vi
Page 279 and 280:
Subject Index Alkyne bridges 148 An
Page 281:
Subject Index 273 Rh(III) cyclometa
show all

Photochemistry and Photophysics of Coordination Compounds

Create successful ePaper yourself

Delete template?

Save as template?