>> '#main: sites/default/files/imagecache/thumbnail_square/images/city_clock.jpg '] }" src="sites/default/files/imagecache/thumbnail_square/images/city_clock.jpg"/>
seems you have an extra blank space
I would probably change your lines
<?php
$path = $fields['field_artphoto_fid']->content;
$pur_path = strip_tags($path);
$node_id = $row->nid;
?>
to
<?php
$path = $fields['field_artphoto_fid']->content;
$pur_path = trim(strip_tags($path)); //remove any extra space at start or end
$node_id = $row->nid;
$debug=true; // easy to change
if ($debug) { echo "Node ID is [$node_id] - Path is [$pur_path]<br>";};
?>
and then
<a href="/node/<? print $node_id ?>"><img id="Thumb_1" class="swapImageDisjoint { sin: ['#main:<? print $pur_path ?>'], sout: ['#main:<? print $pur_path ?>'] }" src="<? print $pur_path ?>" /></a>
should work (I use echo instead of print but it does not matter). (Note: I use <?php just to be sure..)
If it does not work and still keep adding extra space, change course and replace the above line with
<a href="/node/<?php print $node_id ?>"><img id="Thumb_1" class="swapImageDisjoint { sin: ['<?php echo "#main:$pur_path" ?>'], sout: ['<?php echo "#main:$pur_path" ?>'] }" src="<?php print $pur_path ?>" /></a>