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EXPLANATION ON NOTATION AND ARRANGEMENT ABSORBING SYSTEM An absorbing system consists of a chromophore or conjugated chromophores, printed in bold face type in Table I, and an atom or atoms, if any, j[.]
EXPLANATION ON NOTATION AND ARRANGEMENT ABSORBING SYSTEM An absorbing system consists of a chromophore or conjugated chromophores, printed in bold face type in Table I, and an atom or atoms, if any, joined to the chromophore or conjugated chromophores, and sometimes, consists merely of auxochromic atoms e.g compound absorbing system notation Rules determine the notation and sequence of absorbing systems, as mentioned below PRINCIPLE OF CITING AND ARRANGING ABSORBING SYSTEMS Rule The more predominant factor in an absorbing system is cited as early as possible Absorbing systems having a more predominant factor are placed later in the tables For example, C:C predominated over C:C as mentioned in Rule 3, and therefore the chromophore of butenyne is denoted such as CiC - CiC (not CiC - CiC), and CiC precedes CiC in the tables PREDOMINANCY OF ATOMS AND BONDS Rule The order of increasing predominancy of atoms or elements is as follows: H,C, and other atoms in the order of ascending group number of the Periodic Table and increasing atomic number in the group Rule The order of increasing predominancy of bonds is as follows: single bond < coordinate bond < double bond < triple bond (An expression a < b indicates that b predominates over a.) NOTATION OF UNIT CHROMOPHORE Aliphatic chromophores are denoted by atomic symbol and sign of unsaturated bonds e.g CiC CiC CiCiC NiN N i N i N NiC NiC N i C i N PiP OiN OiCiC OiAs SiC SiCiS SiCiN SiCiO Nitro and azoxy chromophores are denoted as Q i N an respectively Chromo- O O phores of carboxylic acid (including ester), and its derivatives of type -CO-X such as amide, halide, and thiolic acid (including ester) are regarded as an unit chromophore and denoted as: OiC OiC OiC OiC ft 61 s Chromophores of carbonic acid (including ester), and its derivatives such as H2N-CO-NH2, H2N-COOH, (HS)2CO, COCl2 are regarded also as an unit chromophore and denoted as OiCO2, 0'.CN2, OiCON, OiCS2, OiCCI Benzene chromophore is denoted by Arabic numeral 6, and carboaromatic condensed chromophores are denoted by Arabic numerals with or without subscript Arabic numerals, respectively indicating the number of atoms in each ring and the number of rings, cited in the decreasing order of the numerals denoting number of atoms e.g naphthalene 66, azulene 75, indacene 655, anthracene and phenanthrene 63 Heteroaromatic chromophores are denoted by atomic symbol with or without subscript Arabic numerals, respectively indicating the kind and number of the hetero-atom, and the notation of the corresponding carboaromatic chromophore e.g thiophene S5, pyridine N6, indene N65, pyrimidine N26, purine N^65, thiazole SN5, benzothiazole SN65 Fulvenoid, quinonoid, and tropoquinonoid structures are denoted by symbols representing the corresponding genuine aromatic chromophore, the exocyclic double bond(s), and the atom(s) joined to the exocyclic double bond(s) e.g methylenecyclopentadiene (fulvene) 5*.C, dihydropyridinone (pyridone) NGiO, pyranone (pyrone) 06.'O, tropone 7iO, methyleneindole N65iC, benzoquinone diimine N'.6iN, naphthoquinone Oi66iO, dihydromethylenefuranone (methylenecrotonolactone) 0.05.C, tropoquinone ^i 7!O PREDOMINANCY OF UNIT CHROMOPHORE Rule The predominancy of unit chromophores is determined by applying the following criteria in series until-a decision is reached a) Heteroaromatic unit chromophores predominate over carboaromatic unit chromophores, which predominate over aliphatic unit chromophores e.g CiC < 66 < N6 b) The predominancy of heteroaromatic unit chromophores is determined first by hetero-atoms contained in the ring, from the point of (i) the predominancy of the most predominant hetero-atom and, if there is a choice, of the subsequent predominant heteroatom(s), (ii) a larger total number of hetero-atoms, and (iii) a larger total number of the most predominant hetero-atom and, if there is a choice, the subsequent predominant hetero-atom(s) Examples for (i) : N6iS < 05, N665 < 065 < S5, 06 < ON5, ON5 < OP5 for (ii): SN65 < SN265 for (iii): SN265 < S2NSS, SeSN2665 < SeS2^eS c) The most predominant is that containing a larger total number of rings e.g < 75 < 63, SN5 < SN65, O i i O < 66 d) The most predominant is that containing a larger ring e.g 5iO < < 7iO, 55 < 65iO < 66 < 75 < 76iO, N5 < N6 < N7iO e) The predominancy increases with the sequence of genuine aromatic, fulvenoid, quinonoid, and tropoquinonoid structures e.g < 0.6.0, 7iO < £i7iO, N6 < N6iO < OiN6iO f) The predominancy of aliphatic unit chromophores is determined first by componental atoms, from the point of (i) the predominancy of the most predominant componental atom and, if there is a choice, of the subsequent predominant componental atoms(s), (ii) a larger total number of componental atoms joined with unsaturated bond(s), and (iii) a larger total number of the most predominant componental atom and, if there is a choice, of the subsequent predominant componental atom(s) Examples for (i) : for (ii): for (iii): g) CiC < NiN < NX < OiC < OiN < O i C i N < O i A s CiC < C i C i C , OiC < OiCiC, OiC < OiCiO, N i C < N i C i N NiCiC < NiCiN The most predominant is that containing a more predominant bond e.g CiC < CiC, NiC < NiC h) The more predominant is that containing a larger total number of a more predominant componental atom(s) joined with coordinate bond(s) or a single bond(s) to the atom joined with unsaturated bond(s) and, if there is a choice, the subsequent predominant componental atom(s) similarly joined e.g OiC < OiC < OiCN < OiC < OiCON < OiC < OiCS2 < OiCSO < OiC < OiCCI , OiN < OiN, NiN < NiN A O NOTATION OF CONJUGATED CHROMOPHORES Conjugated chromophores are denoted by the notation of componental unit chromophores joined by a hyphen e.g CiC-CiC, OiC-CiC-CiO, OiC-66-CiC, Q*.£>N66-CiO When there is a choice, the direction is so chosen as to make the most predominant chromophore and, if there is a choice, the subsequent predominant chromophore(s) come as early as possible N * r* e.g CiC-CiC, OiC-6